Air sealing question

[mithesaint]

I have a leaky, builder grade house. It was built in 1997, as cheaply as a house could be built at that point. Windows are poor quality, doors are poor quality. It's decently insulated, but not air sealed at all.

From the inside of my house, there is drywall, then a 2x4 studwall with R13 fiberglass, then a layer of blueboard insulation, then vinyl siding. The seams of the blueboard are not taped. No OSB or plywood sheathing, no housewrap. When the wind kicks up, it finds the seams in the blueboard and works its way into the house.

I know that the best solution would be to pull the siding, sheath it properly, replace windows and doors, foam, then housewrap. Unfortunately, that's a huge job, and just not in the budget right now.

Would it be worthwhile to simply unhook the siding, and tape the seams of the blueboard? The siding is 17 years old, and while it's pretty faded, it's not too brittle yet. I was going to use the foil tape, and have some that's rated for cold weather usage.

Thoughts? I'd like to eventually have an energy audit done, but am going to wait until I've eliminated some of the major leaks, like the lack of housewrap. We don't have a state funded program that I know of, and I'm not spending hundreds of dollars for someone to tell me something I already know.

 

[EatenByLimestone]

I'd seal it inside. Drywall is an air barrier. Work on receptical boxes and plastic over the windows.

 

[velvetfoot]

I'm curious: how thick is the blue board?

In a related matter, I've just started using a foam gun. It's by Great Stuff, but apparently other mfrs may be used. There are other mfrs of foam guns too, of course. Anyway, I love it. No sticky mess anymore. No wasted material.

 

[EatenByLimestone]

We use great stuff guns too. We usually don't use their foam though. Rodents will chew through it. Ours is pepper laced.

 

[peakbagger]

I would suggest getting an energy audit done and targeting the highest payback areas. Between a blower test and thermal camera I expect there are a lot of low hanging fruit.

 

[velvetfoot]

We use great stuff guns too. We usually don't use their foam though. Rodents will chew through it. Ours is pepper laced.

I didn't realize there was such a thing.

 

[EatenByLimestone]

Once again I can't post links... Google wildlife control supplies for the company and IPF Foam for the product search.

 

[flyingcow]

As pointed out above, work on tightening up the outlets, ceiling fixtures. Use the shrink wrap on your windows, that in itself will make a huge difference. If you can pull inside trim off windows and doors and foam or caulk around them.

 

[semipro]

I disagree with the drywall-as your-air seal approach for your situation. Yes, you can build airtight drywall. However, this is only done right during construction and requires sealing between drywall and studs and at the top and bottom plates. You can't do this well without ripping out all the drywall. Plugging outlets is just going to increase the airflow elsewhere.

I think you're efforts would be better spent beefing up the existing, although poorly installed, air barrier. Taping seams is a good start. There are special tapes made by the foam board manufacturers that you may want to consider rather than the aluminum tape. I know Owens-Corning makes one. I've also found that Tyvek tapes works well on foam. I am concerned about foam board shrinkage and long term tape adhering though.

Personally, if I was going to take the time to pull back the vinyl I'd go ahead and add another layer of foam and seal around fenestrations, sills, etc. Several thinner layers with offset joints is preferred to compensate for foam shrinkage.

 

[mithesaint]

@EatenByLimestone - I've done some work with sealing up the drywall, but I think that's going to give limited improvement at best. Most of my house is carpeted, and I don't have easy access to the lower edge of the drywall. I've pulled lots of trim off and sealed underneath, and gone around most of the outlets, but the air just finds another way inside.

@velvetfoot - the blue board is 1/2" thick.

@flyingcow - do you have a brand of the window film that you like? I've used it in the past, but with limited success. I also have 3 and 4 year old daughters, as well as a dog who HATES the mailman and UPS guy. Most of the plastic ends up with holes in it anyway, unfortunately.

@semipro - I've heard the opposite about the Tyvek tape. I'm gonna give the aluminum tape a try, and check it after a year. I'm not pulling the siding all the way off the house, I'm just going to unhook the bottom of each piece and work on it that way. I don't have the proper ladders and scaffolding to bother with trying to put siding back on after taking it off.

Thanks for the thoughts.

 

[semipro]

@semipro - I've heard the opposite about the Tyvek tape. I'm gonna give the aluminum tape a try, and check it after a year. I'm not pulling the siding all the way off the house, I'm just going to unhook the bottom of each piece and work on it that way. I don't have the proper ladders and scaffolding to bother with trying to put siding back on after taking it off.

Since you're putting a lot of faith in the tape I'd strongly suggest you use the right one. I've used the aluminum tape, Tyvek tape, and Owens Corning tape on your sort of applications over the last 14 years and had much better luck with the Tyvek. My concern with aluminum tape is that it may not stretch as the foam shrinks. I realize your foam may have shrunk some already but it may shrink more.
Article on foam shrink at Building Science site:
http://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=1&cad=rja&uact=8&ved=0CB8QFjAA&url=http://www.buildingscience.com/documents/published-articles/pa-foam-shrinks/at_download/file&ei=qD_iU72SM9LpoATkkYGIAw&usg=AFQjCNGuLqWiy5Z9-oHdQ-G0N33hfC5veQ&bvm=bv.72197243,d.cGU

If you do look into the tape issue further I'd be interested to find out what you learn.

 

[shoot-straight]

my jaw is on the floor that there is no wood product sheathing. i had no idea homes were built with just foam.

my .02$ on the subject- it makes no sense to pull all that siding off and not sheath and wrap it. save up and do it right. even if its one side of the house at a time (most windy side first). you can hit alot of areas when doing so. i had a house built 9 years ago. boy, do i wish i could do that over again. id start with hiring a different contractor... im still fixing shortfalls. my new (competent) contractor used zip tape alot when doing some wall sheathing work. expensive, but good stuff.

 

[semipro]

my jaw is on the floor that there is no wood product sheathing. i had no idea homes were built with just foam.

Our house is built that way and its a rather well constructed house.
Sheathing is only needed structurally to prevent racking or as a base for siding attachment. Sheathing can be used as an air barrier also but only if sealed well.

Our house has sheathing at the corners for the racking and the cedar siding attaches to the studs. The 1/2" foam attached to the outside establishes the air barrier. It also adds some thermal insulation.

 

[woodgeek]

To the OP.....have you airsealed the attic and basement yet? The drafts you feel are often a small fraction of the drafts you don't.

Also, can you compute your home heating index? It is total seasonal heating BTU (from bills) divided by heating degree days (from the net), divided by conditioned square footage. This # can allow you to estimate how leaky or badly insulated you are.

 

[firefighterjake]

my jaw is on the floor that there is no wood product sheathing. i had no idea homes were built with just foam.

my .02$ on the subject- it makes no sense to pull all that siding off and not sheath and wrap it. save up and do it right. even if its one side of the house at a time (most windy side first). you can hit alot of areas when doing so. i had a house built 9 years ago. boy, do i wish i could do that over again. id start with hiring a different contractor... im still fixing shortfalls. my new (competent) contractor used zip tape alot when doing some wall sheathing work. expensive, but good stuff.

Same here . . . mind is blown.

I cannot imagine not having wood sheathing.

 

[Mt Bob]

Good info here.Have a story.Many years ago back in MD I remember expensive houses,with security systems,being robbed.Took a knife,cut through siding,kicked in foam and drywall.One reason motion and heat sensors became popular!

 

[mithesaint]

@semipro - I'll see if I can find the Tyvek tape. I had read a few random comments online where it didn't work for people, and when it wasn't on the shelf at Lowes, I stopped looking. I figured it wasn't there for a reason. I'll take another look.

@shoot-straight - I felt the same way when I discovered that. This is my second house, and I never thought to check for sheathing. I knew the windows and doors weren't very good quality, but I was blown away the first time I unhooked a piece of siding. I know that it's technically acceptable per the engineering standards, and it has the wood in the appropriate places to prevent racking, but I still wish it was there. I live in the boonies, and there's lots of people that like to practice shooting. I think OSB would slow down a stray bullet better than foam. That, and we live in tornado country. Granted, if that ever happens we should be in the basement, but what if we're on the way to the basement and a 2x4 comes through the wall? I'm in total agreement on doing it the right way, and doing it once. However, I'm a few years away from doing that. Pulling off the old siding, replacing windows and doors, putting up sheathing and insulation and air sealing, then putting up new siding is gonna be a huge chunk of change, and I don't have the time or tools to do it myself. I did it on my old house, but that place was half the size of this house, and I didn't have any kids at the time. This house is twice as big, I work more hours, and I have two small kids. I'll have to pay someone to do it, and it's gonna be expensive. That's why I'm working on little things right now.

@woodgeek - I'm almost done with the basement. The attic is next, probably next year unfortunately.

86020000 approx btu from wood pellets/5681 HDD= 15141.7/2412 sq ft = 6.28. I guess that puts me at moderate, although I don't know how much propane I burned in December for three days when the stove was broken, or how much I burned in the polar vortexes when the stove couldn't keep up. Oh, and we occasionally ran a space heater in the bathroom. That's gotta put me near the 7 mark? Either way, not great.

 

[woodgeek]

86020000 approx btu from wood pellets/5681 HDD= 15141.7/2412 sq ft = 6.28. I guess that puts me at moderate, although I don't know how much propane I burned in December for three days when the stove was broken, or how much I burned in the polar vortexes when the stove couldn't keep up. Oh, and we occasionally ran a space heater in the bathroom. That's gotta put me near the 7 mark? Either way, not great.

Actually, if the math is correct, it puts you better than 70% of US housing stock, and would have gotten you an energy star rating in 2005.
Did you use 'output' BTUs for the calculation, not input BTUs? How many lbs of pellets did you use?

I'd still do the basement and attic and get a cheap blower door done before I tackled the wall sheathing. Basement and Attic (me DIY and some pro help) got me to ACH50=5. Much more airsealing than this and I would need winter ventilation, with diminishing returns on energy costs or an expensive HRV.

 

[mithesaint]

That was input BTU. I used about 253 bags, and used 8500 BTU/lb. No idea how many propane btu or electric btu we consumed. Not many electric, but propane was hard to tell.

 

[woodgeek]

I think the correct number for the Home Heating is BTUs delivered to the space, I think you want to use output BTUs, prob 10-15% lower than your pellet figure. I suppose we could guess you added 10-15% of that with propane and space heaters, and still figure you are 6-6.5, a respectable figure.

Its not clear to me that you have a significant amount of air leakage. It is very hard to figure out where air leaks are occurring, unless you've got a square foot opening in your attic, or daylight shining through into your basement.

I would not invest a lot of effort in taping your foam sheathing until you have an airsealed attic and a blower door that says that you still have some significant leakage left.

For refereence, airsealing my 1960 house (attic basement and weatherstripping the windows) dropped my HHI from 12-ish to about 8-ish, and then adding some insulation has got me down to about 6 or so.

 

[mithesaint]

Interesting. Love learning new stuff.

I discovered the lack of sheathing and airsealing in the process of installing the stove after I got shocked with propane bills the first winter. I had to open up the wall to move a drain pipe, and discovered the lack of osb, and a pretty decent breeze coming through a hole in the drywall. At that point, I just assumed that I had major issues, but the numbers aren't as bad as I thought they would be, especially considering the amount of wind I get living in the middle of nowhere. I think I'll still tape the horizontal seams because they are simple to get to, and then work on the attic. Thanks for the advice.