Author Topic: Insulation in Existing Walls (Read 5267 times)

beard423

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Insulation in Existing Walls
« on: August 09, 2015, 01:58:28 PM »
I recently purchased a 1966 Ranch-style home in MMM's stomping grounds, Longmont, CO. I just had an energy audit ($60 out of pocket, subsidized by city/county), and the auditor confirmed what the home inspector had told us previously... we have no insulation in our walls. I've been researching various ways to address this, blown-in cellulose and spray foam seeming like ok options. The problem with both would be you either have to remove the drywall completely, or drill holes and spray and pray that you fill the cavity completely. Contractors are charging quite a bit for the service, so I'd like to diy this thing. Foam seems prohibitively expensive, and the method error-prone for diy'ers, so I'm leaning towards cellulose. This will require cutting 2-3 ~4 inch holes between the stud cavities and spraying in cellulose with sort-of a reverse vacuum. I've read that Home Depot offers one of these machines, but they're relatively ineffective for the dense packing you need for wall installation.

Does anyone have experience with this type of installation? What do you guys think a mustachian should do in such a dilemma? Thanks for the feed back in advance.

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Re: Insulation in Existing Walls
« Reply #1 on: August 09, 2015, 03:00:00 PM »
We had blown cellulose into our exterior walls (not DIY), but done from the outside in our old place.Depending on your exterior material, it may make sense. for example if you have siding that is easily removed and replaced you can do the drilling and then the patching will be invisible once the siding is replaced.

You may never know if the cavities are all completely filled though you might be able to see cold spots with a thermal camera on a really cold day. Not sure what you'd do if you found some spots after the insulation was installed.


If you are really going to DIY, I can't imaging removing the drywall and spraying in foam would be an easy option. The blown in route I think is more reasonable as a DIY.
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Re: Insulation in Existing Walls
« Reply #2 on: August 09, 2015, 06:26:47 PM »
If I was planning on staying there, I would remove the drywall and then insulate. That's really the only way to ensure complete coverage.

If your DIY skills include drywall, your costs will be insulation, drywall, and mudding...it's a lot of work, but in the end may be less expensive than paying someone to blow in insulation. And, of course, you will have the satisfaction of knowing that you have 100% insulation coverage.

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Re: Insulation in Existing Walls
« Reply #3 on: August 09, 2015, 10:14:55 PM »
You would probably get a better return on your time and money by upgrading your attic insulation, and using foam tape and caulk to eliminate any door and window drafts.
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Spondulix

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Re: Insulation in Existing Walls
« Reply #4 on: August 09, 2015, 11:49:02 PM »
Years ago we had professional spray insulation from the exterior. We recently replaced drywall in the kitchen and found the blown in insulation wasn't complete coverage - some cavities were close to full and others had large gaps. We ended up taking out the blow-in and redoing the insulation.

Another issue with blow-in is that the exterior never matched (it's hard to color match to faded ext paint, and the texture is slightly different). I would recommend insulation from the inside (replacing drywall), if possible. The only thing is you might be opening up a can of worms if you find any other issues (plumbing, electrical, mold) but it's also an optimal time to do those kinds of changes.

ShoulderThingThatGoesUp

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Re: Insulation in Existing Walls
« Reply #5 on: August 11, 2015, 08:31:26 AM »
I've realized we don't seem to have insulation in between the drywall and the exterior brick. But our total gas bill for the past twelve months has been $1000. So it's pretty hard to come up with an insulation project that's likely to have a good payback - especially since eliminating air leaks won't be possible. Right?

zolotiyeruki

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Re: Insulation in Existing Walls
« Reply #6 on: August 11, 2015, 09:59:22 AM »
I've realized we don't seem to have insulation in between the drywall and the exterior brick. But our total gas bill for the past twelve months has been $1000. So it's pretty hard to come up with an insulation project that's likely to have a good payback - especially since eliminating air leaks won't be possible. Right?
Is it a brick facade, or an actual brick wall? I know our house in TX (90's construction) had a gap between the framed wall and the brick, with insulation inside the 2x4 wall.

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Re: Insulation in Existing Walls
« Reply #7 on: August 11, 2015, 09:14:57 PM »
At this point I've replaced every 2nd floor exterior wall in my 100 year old house in order to insulate. My house is balloon framed so I was also able to blow insulation down into the 1st floor walls (mostly). It's a lot of work and dust but when you live in Wisconsin and have had winters with $300 heat bills you roll up your sleeves and get to work. In your case I'd say punch some holes and blow some in without tearing it all out. I'd also insulate the sill plate and crawl around in the basement looking for air leaks. I found multiple places that I could see daylight through, and one window with faulty glazing that had a 1" wide gap at the top.

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Re: Insulation in Existing Walls
« Reply #8 on: August 13, 2015, 12:35:18 PM »
If you're going to re-do the siding any time soon, it's easier (probably cheaper?) to add exterior insulation.

Telecaster

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Re: Insulation in Existing Walls
« Reply #9 on: August 15, 2015, 03:04:58 PM »
I recently purchased a 1966 Ranch-style home in MMM's stomping grounds, Longmont, CO. I just had an energy audit ($60 out of pocket, subsidized by city/county), and the auditor confirmed what the home inspector had told us previously... we have no insulation in our walls. I've been researching various ways to address this, blown-in cellulose and spray foam seeming like ok options. The problem with both would be you either have to remove the drywall completely, or drill holes and spray and pray that you fill the cavity completely. Contractors are charging quite a bit for the service, so I'd like to diy this thing. Foam seems prohibitively expensive, and the method error-prone for diy'ers, so I'm leaning towards cellulose. This will require cutting 2-3 ~4 inch holes between the stud cavities and spraying in cellulose with sort-of a reverse vacuum. I've read that Home Depot offers one of these machines, but they're relatively ineffective for the dense packing you need for wall installation.

Does anyone have experience with this type of installation? What do you guys think a mustachian should do in such a dilemma? Thanks for the feed back in advance.

I've done the cut the holes and blow it in thing. It wasn't particularly difficult, but I'm honestly not sure how effective it was.

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Re: Insulation in Existing Walls
« Reply #10 on: August 19, 2015, 08:13:37 AM »
I've realized we don't seem to have insulation in between the drywall and the exterior brick. But our total gas bill for the past twelve months has been $1000. So it's pretty hard to come up with an insulation project that's likely to have a good payback - especially since eliminating air leaks won't be possible. Right?
Is it a brick facade, or an actual brick wall? I know our house in TX (90's construction) had a gap between the framed wall and the brick, with insulation inside the 2x4 wall.

Actual brick wall. The house was built in 1910.

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Re: Insulation in Existing Walls
« Reply #11 on: August 19, 2015, 09:46:44 AM »
I've done the cut the holes and blow it in thing. It wasn't particularly difficult, but I'm honestly not sure how effective it was.

As someone who lives in a very cold climate, additional insulation done correctly almost always pays off if you live in an area with expensive heating costs. You only pay for insulation once...but you pay for heat forever.

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Re: Insulation in Existing Walls
« Reply #12 on: August 19, 2015, 10:56:31 AM »
First off, blown in insulation is a terrible idea. Older homes do not have a vapor barrier between the warn/cold inside/outside areas of the house. Without this vapor barrier you will get condensation in your walls, which will lead to mold problems.

You lose as much as 35% of your HVAC through walls. A very well executed insulation plan, meaning taking out all the drywall - insulating and installing a vapor barrier, would reduce energy loss by a maximum of 70% meaning your heating bills have could be lowered 25%. 4 months of heat at an average cost of $285 (bills ranging $220 to $350) you are looking at saving about $70 per month and maybe $35/month for your 4 months of AC. So roughly $420/year.

To save energy costs, go in this order:

-Air seal all windows, pluming vents, electrical devices, chimney. DIY - $100 (save 10% - $170/yr)
Payback <1 yr

-Insulate the hell out of the attic - DIY - $500-800 - (saves ~ 28% - $470/yr)
Payback 1-2 yrs.

-put storm windows over your existing windows - DIY - $1800 (assumes 18 windows at $100/window
saves about 12% - $200/yr)
Payback 9 yrs.

-Replace the HVAC system with a more efficient one - $4500 - (75 to 95 AFUE - Save 20% - $340/yr
Payback 13 yrs.

-insulate walls - DIY $6000 - $10,000 ( save 25% - $420/yr)
Payback 14 yrs. to 24 yrs.

- New triple pane windows - $5400 (18 windows at $300, save 20% - $330/yr)
16 yr payback

Vic99

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Re: Insulation in Existing Walls
« Reply #13 on: August 22, 2015, 08:26:41 PM »
As far as the order of what you should focus on, Index about nailed it.

Air sealing should be first. Stopping warm air from moving out or in is number one. In an older house, you don't have to worry about it being too tight, you'll never get it all, but you can slow it down. Over the course of several years I have hit parts of my 1920 house basement, walls, windows, and attic with caulking and spray foam. Honestly, I have EASILY covered 4 ft x 4 ft area.

Two months ago the energy audit guys (Mass Save) here in, well, Massachusetts, did a blower door test, professional air sealing, then another blower door test. Try and get that.

Next hit your attic, probably R-40 ish would be fine. IF it is properly air sealed, doesn't much matter what you use as long as a vapor barrier is used where appropriate. If not air sealed, don't use fiberglass - only insulates, but does not stop air flow.

Good luck.