[Mark Harvey]

Exterior insulation

For a re-siding job using vinyl over wood, my clients wants added insulation. I know of a wrap type (Krona) and several sheet type materials (Plasti-span & Silver foam, etc.). All claim to be the best and should do the job. What would be your recommendation and why? thanks.

 

[Windows on Wash]

Depends on the interior wall construction and what is behind the wood siding.

You don't want anything that is a Class I vapor retarder if you have and interior one because it won't dry to either side.

More details are required.

 

[jagans]

Adding insulation like that does not accomplish much because it is non contiguous. Air infiltration voids the gain. It helps support the siding though. EIFS is another story. I would check out the house with an IR camera and tell them where they are suffering heat loss. You would be surprised how much you can lose around a poorly set door, holes in the foundation etc. etc.

Poor windows are usually the real culprit.

 

[Windows on Wash]

Adding insulation like that does not accomplish much because it is non contiguous. Air infiltration voids the gain. It helps support the siding though. EIFS is another story. I would check out the house with an IR camera and tell them where they are suffering heat loss. You would be surprised how much you can lose around a poorly set door, holes in the foundation etc. etc.

Poor windows are usually the real culprit.

Big +1 :thumbsup:

If I had a wooden nickel for every BS insulated siding claim...I would be a rich man.

Well said James.

 

[Mark Harvey]

siding

Gents, I appreciate tyour replies. The building is a cottage, 800 sq. ft., 2x4 construction with the old aluminum slider windows. It was purchased by a young fellow (first house) and he is finding the heating bills to be on the high side. His call to me was about insulation and siding. I am strongly suggesting window replacement and additional attic insulation (now R12). Where I am the recommended amount for the attic is R 40 or better. If he still wants to add insulation and new siding, I'll do it but any other ways to insulate the place better would be his primary desire. Suggestions?

 

[Mark Harvey]

I have received some replies but am looking for opinions on the best way to re-side a small house. My client wants to re-side over existing wood siding and add some type of insulation between the old siding and the new vinyl siding. The more I look into options the more negatives I hear. The house is 2x4 construction with the old aluminum slider windows. What I proposed is , first ... replace the windows with updated weather tight windows. Next is to add attic insulation (currently R12) to R 40 or better. Then the walls.??? I'd prefer to strip the old siding off, check the R value of the existing walls, add insulation and re-side. I'm not convinced that siding over existing siding is the best way to go. One reason is that there is still a void between the two siding surfaces (wood & Vinyl) even though there would be some type of insulation between the two. The primary conern seems to be the insulation ... or lack of. I just want to do the client the best for them. All suggestions are very welcome.

 

[Windows on Wash]

I think you are right. Best to pull the exterior cladding and get intimate contact to the wall surface.

 

[joecaption]

And it's always best to replace the windows before the siding.
There going to save more money in HVAC cost by just doing that then the whole siding job.

 

[r.mills]

I used to side houses 12 years ago. On a 2x4 framed house going to vinyl we always convinced home owner to replace all windows with vinyl 2x6 windows, then stripped off wood siding, added 2" T&G rigid styrofoam, tuck taped seams then put vinyl siding over that. Need like 3.5" nails I think after.

 

[woodworkbykirk]

we only use 1 " foam here. a while back several builders were using 2" foam but were having major issues with the siding sagging after a short period of time. the foam doesnt support the siding nail from drooping under the weight of siding. even more so with wood siding and fibre cement.. so its no longer allowed

 

[Mark Harvey]

siding

If I were to go with the 1" insulation, there would be a gap between the siding and the outer edge of the 2x6 window frame. How did you account for this?

 

[Mark Harvey]

Is there a better way to lessen the possibility of sagging siding?

 

[joecaption]

I guess it's just me but I'd never suggest using that thick a foam, in fact I'd avoid it. Reason being the vaper barrier needs to be on the inside not the outside.
Only time I've used foam is fan fold over old siding to level out the wall.
Using foam that thick you would have to build out ever bit of trim around every door window to make up for the space and use 3" roofing nails.

 

[Mark Harvey]

siding

Joe, What would you suggest if not the foam board?

 

[joecaption]

Just Tyvek or insulated siding.
Once they see the price of insulated siding they may change there mind.
You would need to use 1" J mouding and out and inside corners.

 

[woodworkbykirk]

i should have mentioned all the houses i side we replace all the windows and doors as well so the wall gets compltely stripped windows and doors removed foam goes on then the new windows go in the opening.. if the odd time we dont remove the old window we install new trim around that to build every thing out for the siding

 

[Gary in WA]

How thick of foam, what is closest city; http://www.buildingscience.com/docu...ld-weather-condensation-using-insulation/view

Strapping strength on foamboard, pp.8; http://www.buildingscience.com/docu...ential-exterior-wall-superinsulation-retrofit

Local AHJ for fire-code (strapping gaps liability); http://bct.eco.umass.edu/publications/by-title/insulating-on-the-outside/

Gary

 

[hand drive]

how old is the house? Until you tear into a section of the wall you will not know for sure. there could possibly be no wall sheathing behind the current wood siding leaving you the option to insulate properly in the wall and then re sheath and then re side with siding of your choice. let us know after you find that out...

 

[Mark Harvey]

The house was built in 1974. It, basically, is a cottage but was built to code. The fellopw who recently bought it had a pre-sale inspection and it all sounds "proper". By this I am assuming (I know, I know) ... that the walls are insulated, probably to an R7, and the sheathing is OSB. I plan to check once I get the wood siding off and if need be, and the client agrees, I will re-insulate from the outside, re-apply the sheathing and do whatever we decide after that. (added foam, foil wrap, tyvek, etc.) As mentioned, all responses and ideas are welcome. My client is a young fellow who wants proper insulation and heat control but is also budget minded. I am trying to get him the best bang for the buck. Thanks.

 

[cleveman]

i have a couple of houses built around '70 with the black "R board" sheathing, probably plywood in the corners, sided with the press board lap siding.

I fully expected to find r-11 in the walls and I found r-7.5. I didn't know 7.5 existed.

So what to do?

Obviously, the sheathing comes off, and the 7.5 goes and 13 goes in, from the outside. Then I thought just use metal bracing on the walls, and re-sheath with 1" t & g xps.

I would also like to add some electrical boxes here and there from the exterior as I go, using old work boxes.

Then I'll side with vinyl through the xps and into the studs (2" nails).

I was reluctant to try this system and I still haven't done it, but I have sided a garage over the R-board since, and I feel better about nailing into the studs only now.

Gotta love an r-18 wall after the 7.5.