Need advice on renovating 60 year old home in Maryland.

[Dave A.]

The plan sounds pretty good overall. Just a few thoughts --

Since you're already insulating under the roof deck with spray foam, why not just fill the rafter cavity with enough spray foam to avoid the need for the 4" insulated panels and a new plywood roof deck above.

Without photos or clearer description, just want to express concern if you're removing attractive divided lite wood windows that might add architectural interest to the house. In which case, good quality storms (low E) and possibly retrofitting the original sash with good weatherstripping might be the better alternative.

 

[NRGarrott]

The plan sounds pretty good overall. Just a few thoughts --

Since you're already insulating under the roof deck with spray foam, why not just fill the rafter cavity with enough spray foam to avoid the need for the 4" insulated panels and a new plywood roof deck above.

Without photos or clearer description, just want to express concern if you're removing attractive divided lite wood windows that might add architectural interest to the house. In which case, good quality storms (low E) and possibly retrofitting the original sash with good weatherstripping might be the better alternative.

I wasn't going to spray foam everything due to the cost. I'm still waiting on an estimate but I think it will need around 7000 board feet.

The house was a Montgomery wards kit house, and the windows were builders grade 60 years ago.

 

[woodgeek]

Seems like you have a handle on the issues and the details....it seemed you were conflating weather barrier, airbarrier and vapor barrier. Tar paper or untaped tyvek (if lapped for drainage) would be the first one, Taped tyvek would be also be an air barrier, but neither is a vapor barrier. Both taped foam sheets and taped tyvek airbarriers can fail over time. Just confused that you were talking about a vapor barrier. No worries.

You are correct that with exterior foam the wall sheathing will be above dew point. Many sheet foams are vapor barriers, so thin foam can be a problem, 2" will be great where you are.

My point was that you can estimate the annual energy savings for going from R-10 to R-20 walls (adding 2" on the outside), by computing the conductive loss per year in BTUs as A*24*HDD/R-value, where A is the wall area in sq ft and HDD are your annual heating degree days (prob 4500-5000 or so). You might be surprised how little difference it makes. In my 2500 sq ft (floor) house 2" of exterior foam on my 2x4 walls would save me about 4.5 million BTU, or maybe $90 of heat a year. Hard to get excited given the amount of work required if your siding is in good shape.

Sorry I missed the window statement in the original post....building out and flashing all the windows is a lot more work than just popping in a new window.

On the wall insulation, your plan makes sense with DIY cellulose, the foam will cover any gaps or defects you might leave in the cavity. If you were considering skipping the foam, I would go for a pro dense-pack job, with IR afterwards, to avoid gaps and to get an airsealing benefit. I would at least get a quote, with the truck mount machines and tools, they can do the job fast and well.

Building out the gable ends with 'ladder framing' seems to be pretty conventional.

 

[NRGarrott]

I'm at 84 million BTU's right now, with 1400 sq ft wall area, and plaster walls with diagonal sheathing yielding r2. Dense pack cellulose would be r12 or 14 million btu's. 2" foam board and loose pack would be r19 @ 8 million btu's. Not looking at furnace efficiency, 84 million btu's is 600 gallons of fuel oil or $2,280 a year, 14 million btu's is 100 gallons of fuel a year, or $389 a year, and r19 would be 57 gallons of fuel and $222 a year. Those are some sobering numbers. I may rework everything I am doing. I can install rigid foam probably cheaper then having cellulose dense packed, but I won't know until Thursday. These are obviously just rough numbers for wall heat loss only, not windows and attic. This is not my forever home, in fact I may tear it down one day and build a nicer one on site.

My siding is 60 year old asbestos that is cracked and allowing water to infiltrate so it has to go. I may have been going overboard with my insulation ambitions after looking at those calculations. It just seems silly to put a new roof, and exterior siding up, with free carpentry labor and not do everything to make the place perfect. Do you know what the minimum depth of foam would be required to keep the interior of the wall cavity above the dew point? I could save a a fair amount by switching from 2" r10 to 1" r5. The window and door details would be easier also.

I am having 2 top rated angies list insulation companies come this week, do you have any particular questions I should ask them? I was planning on letting the guy give me his take on the best way to do it, then present what I have come up with, and hopefully we will be pretty similar.

Thank you for your help with the barriers. You hit the nail on the head, I knew there was a difference between water, air, and vapor barriers, but I didn't know which was which. I'll probably go with taped tyvek to form an air barrier. I doubt the house will ever be tight, but I can certainly tighten it up.

 

[NRGarrott]

Here are a couple pictures of the exterior as is.

 

[jacobtay]

I'll probably replace my windows with builder grade vinyl when I re-side the place.

I believe that is a great idea to do that, I had my pane windows replaced with vinyl windows, moreover, I did them myself. However, as you are a part time carpenter, you might be aware about how to do that, I guess. I had earlier done this with the help of a blog writer which helped me understand the process and made my work a lot easier. The process was explained so appropriately that I hardly faced any issues while replacing the windows. I got to learn about this from http://valuewindowsdoors.wordpress.com/2013/09/18/vinyl-window-installation-guide/ and was able to follow it too Hope this will be of help to you.

You might need help of contractors and man power but still one needs to know how it is done and it is helpful in reviewing while it is being done. I had done this just few weeks back and I see no gaps, no cracks, no air passage. Windows are the eyes of a home and they should be very well taken care of, hope I am right ?

 

[jacobtay]

Looking forward to more pics!

 

[DamienBricka]

One thing I've found is that board foam is far cheaper than spayed foam per unit volume, at least given my local rates provided by spray foam contractors. So, if there's anyplace you can install board foam yourself instead of spray and you're willing to put in the effort...

I insulated my home 10 years ago with 3" of icynene foam (R10) if I had to do it all over again I would have use Polystyrene Insulation foam. I would have been able to double my insulation power for the same cost by using elbow grease

 

[woodgeek]

My siding is 60 year old asbestos that is cracked and allowing water to infiltrate so it has to go. I may have been going overboard with my insulation ambitions after looking at those calculations. It just seems silly to put a new roof, and exterior siding up, with free carpentry labor and not do everything to make the place perfect. Do you know what the minimum depth of foam would be required to keep the interior of the wall cavity above the dew point? I could save a a fair amount by switching from 2" r10 to 1" r5. The window and door details would be easier also.

Ok, So, I would adjust the numbers slightly. With thermal bridging by the studs and framing (which take up 25% of the area and are R-3 or 4), the effective average R-value of a cellulose filled 2x4 wall is closer to R-10. I **think** that 1" of sheet foam would be aok on the exterior dewpoint wise, and, without any thermal bridging, add on. So, maybe R-10+3 to R-13. Two inches would make R-16.

Even if the financial improvement from the foam looks ok using oil heat, you might consider the financials of a heat pump in your climate.

Also, don't be fooled by 'insulated siding', which had no benefit because of the venting behind.

 

[Floydian]

Do you know what the minimum depth of foam would be required to keep the interior of the wall cavity above the dew point?

From my favorite building expert: http://www.greenbuildingadvisor.com...lating-minimum-thickness-rigid-foam-sheathing

I suspect you are familiar with the site but if not this is also a good read: http://www.greenbuildingadvisor.com/blogs/dept/musings/how-install-rigid-foam-sheathing

Beyond the energy savings of adding exterior foam another big plus is the added comfort. A warmer wall is just nicer to be next to. Also, from a durability standpoint, having a ventilated rainscreen behind the siding adds a large safety margin for dealing with bulk moisture (assuming proper window and door flashings integrated into the WRB).

To save on rigid foam goods you might contact http://insulationdepot.com/ to see what they might have close to you. I bought a bunch of polyiso a couple of years ago for $.65 sq ft delivered for 2.5".
You would save a bit if you can pick it up locally. I'd say 80% was in very good condition.

Noah

 

[GaryGary]

Hi,
It sounds like you have the heat loss calculations in hand, but this calculator may save a little wear on your calculator:


It makes it quick to make trades on insulation and infiltration changes in the context of the full heat loss for the house. Shows you which areas stick out on the heat loss.
http://www.builditsolar.com/References/Calculators/HeatLoss/HeatLoss.htm

It uses the same formula as WoodGeck mentioned above.

I'd consider bringing your dog into this conversation -- he looks pretty wise.

Gary

 

[Galt]

Used to build in Maryland's critical areas so I'm familiar with your challenges. To save some dough try recycled foam board. I've had no problem finding foil faced ISO for less than half retail on the Eastern Shore and on-line. Had a small shop (16x32) that I needed to heat for cheap so wrapped with 2" ISO foam board (two layers of 1" with seams staggered) after caulking all of the plywood sheathing seams and construction joints (wall plates, corners, etc.). Good Stuff'ed any irregularities, overlapped the corners, foil taped both layers of the foam seams and extended to the soil line, just below the bottom of the insulated wood deck. Attic got the same treatment sort'a, foam on bottom of attic deck joists and then drywall. Joists were 2x10's overlaid with 2x4's standing on edge and run perpindicular, screwed through into the joists every 24" where they crossed and then the void was filled with blown in cellulose before decking. Originally intended to insulate the wall cells before covering with a layer of OSB and HDF slot wall, but once the envelope was complete we were happily surprised by how incredibly efficient it was and never bothered.

A kind of sully point double entry foryer was added and the space was litterally kept at 50 degrees all winter long with nothing more than the residual heat from the ballasts of one bank of eight fluorescent shop lights. Doesn't say much for the efficiency of the ballasts but a pleasant surprise all the same. This was a small boat building shop with a wooden deck floor that mirrored the attic deck to some degree, but it had a H.D. continuous vapor barrier on the earth side, two layers of foam and some surplus vermiculite to fill the voids. The interior finish was two coats of either Kilz or Zinzer primer that is rated as a vapor barrier. Nasty stuff to work with but quick drying and and it places the vapor barrier as close to the conditioned space as is possible. Since the main floor was a double layer of T&G plywood (attic had a single layer) they also got sprayed with the walls and ceiling before getting an epoxy finish (I think the attic was a cheaper acrylic).

The thinking was that moisture needed to be prevented from migrating into the envelope and condensing from either side (especially given the presence of recycled newspaper). The contiguous foil wrap that the taping and ISO board provided would work to prevent outside-in while the primer kept inside-out from occurring. There were numerous solar light tubes but no windows in this building so the only real air leakge left to guard against was at the doors, and these got storms and all kinds of weatherstripping and seals. Ventilation was critical and specialized, but not relavent to your situation other than to stress that trying to create an Igloo cooler demands good air exchange, and had any real moisture been trapped or found a way to enter the envelope and condense, we would have doubtless had a serious mold problem and a serious breakdown of thermal efficiency in the cellulose. Used the building through seven years of varied weather before moving it and there was no evidence of any moisture issues what so ever.

We used peel and stick rubberized foil flashing to tape the foam board seams (wall framing was 24" O.C. and sheets were stood up). Got a great deal on a bunch of it at auction plus it's self sealing when ya poke fasteners through it and in this application all of the foam board fasteners got covered as well. Salt treated yellow pine strapping was screwed vertically over the tape to allow vinyl siding attachment. I've built houses this way in the past and the only real PITA is the extra work at window and door penetrations. We spent a lot of energy making sure that windows and siding were installed per spec, and that envelope penetrations were properly flashed and sealed. Workmanship and attention to detail is critical 'cuz the little things that a non-English speaking sub-contractor's mechanic might overlook is exactly the kind of stuff that gets magnified quickly in this type of application.

Love the spray foam but hate the price. It just can't hang with half priced ISO, even with all of the extra stuff that we chose to do. Also meant to mention that the shop had a 6/12 pitch raftered roof with a high reflectivity standing seam metal finish. Don't recall the specs off hand but something over 95% radiant rejection I think. Even though the attic was unconditioned space it stayed quite reasonable in the dead of summer with nothing but passive ventilation (vented soffit and continuous ridge vent).

Good luck with your project.

 

[woodgeek]

So, I think you might look at a scenario that looks more like a conventional energy retrofit than a deep energy retrofit, just for comparison sake on cost/labor/ROI.

The conventional retrofit approach would be:
1) Cellulose the walls.
2) Airseal the rim/sills and attic floor (requiring pulling up the attic decking), and mucking around underneath.
3) Upinsulating the attic floor to code R-value, maintaining a generous storage area with new decking with some sheet foam underneath, and burying the rest in blown cellulose to R-50...and maintaining the attic venting, go for conventional soffit-chute-ridge if it doesn't exist now.
4) Ditch the oil heating system in favor of (assume no nat gas) a heat pump system. This could be mini-split(s), which are very DIY-able if you find an HVAC tech to do the final pump down line hookup for the cost of the time. I prefer ducted systems for comfort (and convention)...this would require running ducts, either in the attic, basement, or new ceiling soffits.
5) if DHW comes from the oil system, switch it to another source, like a HPWH (with local utility rebates).

(except for 1, this is exactly what I did to my 1960 split level over the last 6 years)

In terms of planning, 2 has to be before 3, and 1 and 2 should be before 4, but other wise order is flexible. all of 1-5 will have 2-5 year simple payback on material costs + even pricing your labor in.

Your roof/siding/window projects are all **separate** from the energy retrofit aspects, and are done as needed for leaks/durability. These projects become much simpler because architectural changes are not required. IMO, this plan would drop you heating BTU load by 50-60%, depending on current airsealing, and your heating+DHW cost by 70-80% (using cheaper BTU sources). Final structure would have energy usage comparable to proper new construction to 2011 energy codes, and half that of existing US housing stock. You would likely have the lowest energy bills on the block for many years to come.

The reason this is the conventional approach is b/c it has the best bang for the buck in terms of labor and materials.

You can try computing the delta cost/savings for each job component.

Creating a sealed, code insulated attic is nice, but a lot more expensive for materials, and requires spray foaming which IMO is not DIY. I could see the case IF you gained a living space, or at least a useable playroom for the kids. With your low 4/12 roof, I don't see that in the card. If you are replacing the roof anyway, and are a master carpenter, you could go one step further and raise the roof height and or slope/add dormers to add useable space to your home, but that would depend on a lot of factors (including adding permanent stair access from below).

Foaming the outside versus not, would reduce the final heating cost by 10%, maybe a couple hundred dollars on oil, or $100/year if switched to HP tech. Siding sounds like it is done, and will be trashed during the wall fill work. I'd look at new cement shingle or cement clapboard versus vinyl, but to each his own.

Getting rid of the oil system was technically complicated, but I feel is the best thing that I have done. I have better DHW service, no maintenance issues/costs/contracts. I have no CO worries, and the replacement, while requiring new hardware, has saved me as much if not more money than the envelope work, and resulted in a much more comfortable and clean house. Even if resale is a long way aways, I figure that fuel oil will not be popular at all 10 or 15 years from now.

 

[Dave A.]

A nice exterior paint job, a new roof, and some landscaping would do wonders for this house. If you're thinking in terms of possibly tearing it down in a few years I cannot see doing all the work you are thinking about.

The windows appear to be wood with triple track aluminum storm sash. Prime and paint the storm sash or replace them. Leave, repair and paint the wood windows. Even as is, cannot see where builder grade vinyl windows are going to be much better than what you have. And right now you have brickmold molding surrounding the windows. Vinyl windows will have no molding. To make vinyl windows look right you're going to have to add trim. Without trim they'll look cheap.

Hard to believe a house of that vintage would have no insulation in the walls. My understanding is that fha and va mortgage requirements of that time, 1950's, required insulation in walls and attics. It was the standard building practice of that period.

Unless it's not showing in the photos, the condition of the siding is not that bad and replacing a few shingles with what looks like stock siding should be possible if necessary, unless there really is no insulation in the walls and then if you really want to replace the siding it becomes more reasonable, since patching and replacing the present asbestos cement after the insulation job would make less sense. Agree with WG about fiber cement vs. vinyl siding.

But again little of this makes sense if there is a real possibility of tearing down the building in a few years and rebuilding.

As far as the windows, replacing what you have (which is in effect dual glazing including the storms) with builder grade vinyl does not make sense to me.

 

[NRGarrott]

I have had 2 insulation contractors come out this week. Both top rated on Angie's list, since the insulation contractors I usually work with are dirtbags. The first one hasn't gotten back to me with a quote yet, the 2nd one quoted me $5700 for 8 inches of open cell spray foam on the underside of the roof deck. This should effectively air seal the attic, and provide r-30 or so. The $5700 comes with a local utility rebate, resulting in final cost of $2800. I need 7200 board feet. I can't buy the spray foam for that cost. I don't want to pull the floor up to air seal, because it is asbestos underneath.

I figured my best option besides spray foaming was to build a 2nd floor above the current attic deck. I would use rigid foam board and osb over that. Polyiso foam board is about 2 dollars a square foot for r-26, OSB is about .25 a foot. So my cost for r-26 attic floor is $1900. I don't know how I would seal the exterior soffits, or the attic stairs.

The oil furnace is 2 years old, and it has a 2 year old Trane AC unit. The DHW is a brand new Geospring Heat pump water heater. I'm thinking my winter heating bills will drop dramatically when I get this quadrafire 3100i in service.

The siding is absolutely done, probably 10% of the shingles are cracked. I'm surprised it doesn't leak more. I have been convinced that I probably won't do rigid foam on the exterior, it just doesn't pay back quick enough. The insulation contractor today let me use his thermal imaging gun. That is one neat tool. You can look at the walls from the interior, and see the studs glowing warm, they provide the most insulation in the walls, so much for thermal bridging.

Dave A this house was built as a summer beach cottage, It was a Montgomery Wards kit house, I can guarantee there is no wall insulation, since I checked with the thermal imager, and I have drilled holes in the exterior walls and the drill bit came back absolutely clean and there is no resistance once you get through the plaster. I'm leaning very heavily towards agreeing with you on the windows. Some of the storms have had the glass switched for screens. I guess I can find someone local to make me new glass. My original plan was to do nothing at all, in case i decided to tear it down, but something has to be done to lower these energy bills. I think the $2800 for spray foam will have pretty quick payback. In comfort if not in utility dollars.

 

[Dave A.]

More info does change things. Didn't realize you had a fireplace or central air. If you're going to be cutting your own wood and it's basically free then the cost of heating looks a lot different. Swapping out the a/c unit for a heat pump would probably make sense if you have to buy your wood, and maybe even if you get it free. Just a midrange quality heat pump should heat you well in the shoulder seasons for a lot less than oil or serve as a lower cost backup than the oil for your wood stove when you can't build fires.

I like the idea of spray foaming under the roof and saving the attic for storage. Nice that the utility offers that rebate. Anyway, beefing up the attic insulation seems to give the largest payback vs. adding it elsewhere.

About the no wall insulation, just wanted you to make sure.

 

[1750]

You've obviously considered pulling up the attic floor and strapping it out to allow you room to insulate your actual living space (vs. creating the much larger envelope by doing that at roof level). For the most bang for your buck, this is probably what I would do. Especially if you aren't sure what your future holds in the place.

If I was contemplating all of the roof work you are describing on a house this size, I might think about raising the roof and creating more useable space on the second floor (you must bump your head a lot as it is!). This would also allow you to use a more conventional and less expensive insulation plan for the roof.

Here are a bunch of options for insulating your attic stairs: http://www.greenbuildingadvisor.com...-insulate-and-air-seal-pull-down-attic-stairs
This one seemed like a particularly good idea to me: http://www.draftcap.com

This is a big project. Good luck!

 

[woodgeek]

I don't want to pull the floor up to air seal, because it is asbestos underneath.

Huh? Loose fill asbestos? Or vermiculite tested to contain asbestos? Other?

 

[NRGarrott]

It is untested vermiculite. I don't plan on disturbing it, so I it hasn't been tested. After viewing Gary's calculator above, I don't think I am going to go with rigid foam board on the exterior anywhere. Even at half prices, it just doesn't make sense. It looks like foam on the roof would save me under 30 gallons of fuel a year. That is assuming I am not burning any wood.

This is always subject to change, but right now I am planning on having the underside of the roof deck spray foamed with open cell at r30 or so. And the gable ends done also, effectively air sealing the attic. Then I will airseal and insulate the very leaky rim joists in the basement. In about 6 months to a year depending on finances I will remove the broken asbestos siding, medium pack the walls with cellulose, and install new siding. Maybe with a rain screen, maybe not. For the windows I will probably just put new weatherstripping on, strip and paint them, then repair and correctly install the storms.

This will not create any sort of super home, or even a very tight one, but it should cut my heat loss though walls and attic from 65.4 million btus to 12.8 million.

 

[woodgeek]

It is untested vermiculite. I don't plan on disturbing it, so I it hasn't been tested. After viewing Gary's calculator above, I don't think I am going to go with rigid foam board on the exterior anywhere. Even at half prices, it just doesn't make sense. It looks like foam on the roof would save me under 30 gallons of fuel a year. That is assuming I am not burning any wood.

This is always subject to change, but right now I am planning on having the underside of the roof deck spray foamed with open cell at r30 or so. And the gable ends done also, effectively air sealing the attic. Then I will airseal and insulate the very leaky rim joists in the basement. In about 6 months to a year depending on finances I will remove the broken asbestos siding, medium pack the walls with cellulose, and install new siding. Maybe with a rain screen, maybe not. For the windows I will probably just put new weatherstripping on, strip and paint them, then repair and correctly install the storms.

This will not create any sort of super home, or even a very tight one, but it should cut my heat loss though walls and attic from 65.4 million btus to 12.8 million.

Sounds logical and cost effective to me. If the storms are shot, getting new low-e ones can be cost effective and gets you an R-3 rather than R-2 window. I would still test the vermiculite, there is plenty that is not loaded with asbestos. The rebate on the attic sprayfoam makes it a deal.

 

[brogsie]

Not sure if anyone mentioned this. Do your utility companies offer any incentives for insulating and other energy saving projects. I live in Mass. We have Mass Save sponsored by the utility co's. They did a free energy audit, paid 75% of the cost to insulate (added 6" to the attic, filled 2x4 walls w/dense pack cellulose), free air sealing attic and basement, free weather stripping on doors, change every light bulb in the house from incandescent to CFL's, $1,000 rebate on an heat pump water heater, $500 rebate on a mini split heat pump. Made an unbelievable difference. Cost to heat the house w/mini split, hot water, dryer and cooking last month was $180.

 

[Floydian]

This is always subject to change, but right now I am planning on having the underside of the roof deck spray foamed with open cell at r30 or so.

I am not saying don't do this as there are plenty of examples of this type of install working fine. Just be aware that there are also risks with this approach.

Here: http://www.greenbuildingadvisor.com/blogs/dept/musings/open-cell-spray-foam-and-damp-roof-sheathing

OSB makes the potential problems worse and you don't have to worry about that but damp roof sheathing of any type is never a good thing. Ideally you want a good vapor retarder (not barrier) between your conditioned space and your open cell foam. The spray on vapor retarders don't seem to be very reliable from what I have read.

Noah

 

[NRGarrott]

Brogsie the local utitlity is willing to foot almost half the bill for sprayfoam.

Floydian damp roof sheathing is a concern of mine. I don't think humidity levels in the home are high, mainly because the oil furnace, quadrafire 3100i, and heatpump water heater all serve to lower humidity levels. The basement has absolutely no water issues, since a french drain was placed last year. The pipes are in poor condition under the first floor, in the basement ceiling, but i am going to slowly change over to cpvc. The house has a new trane ac unit, that I hope will help dehumidify in the summer also. The roof is small enough that I could cover it in ice and water shield if necessary. I think this would drastically reduce any solar driven moisture into the attic.

 

[Dave A.]

I'd use the closed cell, and make sure the contractor is good and knows what he's doing. Be aware of the risks of not letting the materials come up to temp, going too fast creating voids, and protecting things from over spray.

 

[NRGarrott]

Dave you foot the bill and I'll use closed cell.