# Outside Air Leaking in From Gaps Where Floor and Wall Meet



## Red Squirrel (Jun 29, 2009)

If the gaps are significant, you could try to spray some foam insulation in there then caulk it in.

The proper way would be to remove the molding and possibly the drywall and put real insulation but that's quite a big mess to get into in a finished home. Sounds like they did not insulate the walls properly.

There may be a possibility the cold air is coming from the basement if the areas between the joists aren't insulated. This is easier to remedy if the basement is not done.


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## benchmarkman (Sep 30, 2009)

There is no basement. Do you have any suggestions for the carpet/wall air leaks. Does shoe molding help insulation or is this only for aesthetics?

Is this the kind of foam insulation you are talking about?

http://www.lowes.com/lowes/lkn?action=productDetail&productId=13617-236-227112&lpage=none


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## Thurman (Feb 9, 2009)

Squirrel is probably talking about something like Great Foam, or another expanding foam. But, I would caution it's use around carpet, this stuff is very hard to remove from carpet. As RS also stated, the proper way would be to remove the baseboard molding, investigate the problem, and resolve it this way. Why not remove one piece of base molding where you feel the most air is infiltrating to see what is in back of it? IF you find the sheet rock high off of the floor, and cannot see or feel any insulation behind the sheet rock, then you have found your problem. You can even cut the sheet rock up to within a half-inch of the base molding height so you can see into the wall cavity better. This area will be covered with the base molding when it is put back into place. Keep us informed, Good Luck, David


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## Gary in WA (Mar 11, 2009)

1. Is the floor over a crawl space or is it a concrete slab?
2. Does the air seems to be from under the bottom plate? This is an easy fix with caulking and backer rod or foam (messy), after removing base board.
3. When you carefully remove an outlet cover face plate on electrical receptacle, can you see insulation in the wall?
Be safe, Gary


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## benchmarkman (Sep 30, 2009)

Thurman said:


> Why not remove one piece of base molding where you feel the most air is infiltrating to see what is in back of it?


You make it sound so easy, which it probably is for experienced people. Now to answer your question of why I have just removed one piece. First I don't know how to remove molding, easily fixed by a google search. Second, I don't know how to reinstall the molding, again easily fixed with a google search. Third, I don't know what I would be looking for unless there is an obvious hole, which I doubt since air is coming in from ALL my walls in the same amount. Finally, even if I did find the problem I'd have no idea how to fix it.



GBR in WA said:


> 1. Is the floor over a crawl space or is it a concrete slab?
> 2. Does the air seems to be from under the bottom plate? This is an easy fix with caulking and backer rod or foam (messy), after removing base board.
> 3. When you carefully remove an outlet cover face plate on electrical receptacle, can you see insulation in the wall?
> Be safe, Gary


1) Concrete slab.
2) What do you mean by bottom plate?
3) NOt sure about this one. Will have to take a look late today.


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## ccarlisle (Jul 2, 2008)

*uh...'Filtration soiling'*

The results of having this airflow through your walls coming out at the baseboards - especially in a condo or an apartment building - will eventually be black lines on the carpet right next to the baseboard, where the air comes in. The air carries pollutants from the air pressure system located in the garage or on the roof in some cases. Either way, the walls are hollow and some buildings are constructed this way.

We call it "filtration soiling" and it's a bear to remove. We charge $2.50 a foot to clean this because it has to be done repeatedly with a brush. The solution is to seal the gap between the floor and the wall. Pry off the baseboards gently, seal the gap with a caulking compound in a caulking gun, replace baseboards with new ones - or take out the nails of the old ones, and put them back with finishing nails. Repaint.

These filtration lines appear sometimes under front doors of condos where the hallways are pressurized and the air comes into the condo underneath the door. Same problem, not the same solution. They also appear along odd walls - on the inside but not the outside, on the living room walls but no the dining room etc...just depends on what walls the architects left hollow.


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## benchmarkman (Sep 30, 2009)

I pulled out the baseboard on the carpet problem and the concrete flooring stops about 1 - 1.5 inches before reaching the wall and there is no insulation. I tried the spray foam and that seems to hav helped a little but no where near perfect. Any ideas? I put a thermometer down there before hand and after 15 minutes it was reading 52.9 degrees farenheight.

The spray foam insulation has done wonders for the gap beteween the wall and my tile.


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## benchmarkman (Sep 30, 2009)

No more ideas for me?


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## Gary in WA (Mar 11, 2009)

I meant to check in the wall cavity for insulation present. You can see fiberglass batt insulation at the gap next to drywall/electrical receptacle box. 

The bottom plate is a2x4 or 2x6 laid flat on the floor holding the upright (studs) framing members in line and spaced, holding the drywall on the wall and the ceiling framing up. A slight gap between the plate/floor can let in a lot of air. Fiberglass insulation is next to worthless in stopping air leaks, you need caulking or backer rod or foam. V

1. What is your foundation wall material, concrete, block, etc.? 2. Does the framing (wood) extend below the concrete floor slab level?
3. Did you check on the wall insulation?
Be safe, Gary


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## benchmarkman (Sep 30, 2009)

GBR in WA said:


> I meant to check in the wall cavity for insulation present. You can see fiberglass batt insulation at the gap next to drywall/electrical receptacle box.
> 
> The bottom plate is a2x4 or 2x6 laid flat on the floor holding the upright (studs) framing members in line and spaced, holding the drywall on the wall and the ceiling framing up. A slight gap between the plate/floor can let in a lot of air. Fiberglass insulation is next to worthless in stopping air leaks, you need caulking or backer rod or foam. V
> 
> ...


1) No idea, how do I find out?

2) Again no idea, how do I find out.

3) Still haven't check that yet.

What is backer rod and foam v? How would caulk work for a 1 - 2 inch gap? The gap is also deep, wouldn't the caulk just fall in the gap and not stop anything?


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## Gary in WA (Mar 11, 2009)

The gap sounds like it is next to the wood framed wall and the concrete slab. If this is correct, there should be a 2x4 or 2x2 in that gap which was installed to keep the concrete slab from filling the stud bays (areas between framing). If it is gone, you may have a 1-1/2" wide by 3-1/2" gap to fill. I don't understand how the carpet was held down at the perimeter without the 2x4 there. Regardless, you need to fill the gap with insulation: http://www.lowes.com/lowes/lkn?action=productDetail&productId=42729-236-263063&lpage=none.
Figure how many feet you need times the depth, times how many pieces to fill the gap. Maybe 3 pieces, 3-1/2" wide, divided by a 4x8' sheet = 13 pieces divided by 3 = 4 fillers, 8' long per sheet, or 32' of insulation. Put those in the gap, install carpet. Does the baseboard hold the carpet down? 

Backer rod is tubing of polystyrene insulation to fill large gaps before caulking over them. It is sold in different diameters which you can braid the make it bulkier, but if you do, it loses some R-value because of the air gaps where it was twisted for the braid. http://www.lowes.com/lowes/lkn?action=productDetail&productId=41298-81-71464&lpage=none

The V was a typo, sorry. With the base board removed, you should see some wall insulation. If not, another project!
Here is some wall framing with bottom plate: page 69, figure 3-55: http://books.google.com/books?id=pD...#v=onepage&q=slab on grade foundation&f=false
Be safe, Gary


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## benchmarkman (Sep 30, 2009)

GBR in WA said:


> The gap sounds like it is next to the wood framed wall and the concrete slab. If this is correct, there should be a 2x4 or 2x2 in that gap which was installed to keep the concrete slab from filling the stud bays (areas between framing). If it is gone, you may have a 1-1/2" wide by 3-1/2" gap to fill. I don't understand how the carpet was held down at the perimeter without the 2x4 there. Regardless, you need to fill the gap with insulation: http://www.lowes.com/lowes/lkn?action=productDetail&productId=42729-236-263063&lpage=none.
> Figure how many feet you need times the depth, times how many pieces to fill the gap. Maybe 3 pieces, 3-1/2" wide, divided by a 4x8' sheet = 13 pieces divided by 3 = 4 fillers, 8' long per sheet, or 32' of insulation. Put those in the gap, install carpet. Does the baseboard hold the carpet down?
> 
> Backer rod is tubing of polystyrene insulation to fill large gaps before caulking over them. It is sold in different diameters which you can braid the make it bulkier, but if you do, it loses some R-value because of the air gaps where it was twisted for the braid. http://www.lowes.com/lowes/lkn?action=productDetail&productId=41298-81-71464&lpage=none
> ...


Thanks for your help. There is no 2x4 there and I guess the baseboard is holding down the carpet, there is nothing else that could be holding it down. All the walls that are on the perimieter are like this. I always thought the carpet was nailed/stapled down? I had Home Depot install the carpet about 1 year ago. Were they supposed to cover this gap with 2x4 or insulation as part of the carpet install?

Are you saying I need to rip my carpet up to install the insulation? You didn't say that but the last step you mentioned was install carpet.

I saw 0 insulation when I removed the baseboards. Where should I have seen insulation? I really didn't see any room or place where insulation would fit.


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## 747 (Feb 11, 2005)

post a pic where you removed the baseboard if you can. Actually lay down and take a pic if you can.


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## benchmarkman (Sep 30, 2009)

Will do. I won't be able to do anything until Saturday or Sunday though.


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## newtownhome (Mar 3, 2015)

Hi

I brought the brand new town home and experiencing the same issue. Could you please advise me if you have any solution without removing the sheetrock and advise what 0 VOC foam and caulk to fill the gaps.

thanks in advance for your help.


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## zeal2005 (Nov 2, 2016)

benchmarkman said:


> Will do. I won't be able to do anything until Saturday or Sunday though.


Hi,

Can you please advise on how you finally managed to get rid of air leakage from carpet & wall joints? I have the same problem and making me go crazy with one of the bedrooms that is getting extremely cold in winter. Kids are falling sick.


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## Windows on Wash (Aug 30, 2011)

You have two options with varying degrees of effectiveness. 

Inside or outside sealing. 

What does the exterior of the home consist of?


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## TinkerDude (Mar 12, 2017)

zeal2005 said:


> Hi,
> 
> Can you please advise on how you finally managed to get rid of air leakage from carpet & wall joints? I have the same problem and making me go crazy with one of the bedrooms that is getting extremely cold in winter. Kids are falling sick.


I just discovered this thread and am adding to this in the hope of re-starting this discussion. We bought a 50-year old house in Boston and got a taste of leaking air/cold bedrooms/leaky window/leaky attic doors when it got really cold. I have been attacking simple problems like re-sealing entry doors etc, using rope caulk to seal gaps but I am discovering that some walls have zero or no insulation (when I was trying to wire a network cable, I realized that an exterior wall had no insulation - just a torn up sheet of what looked like to be aluminum foil. 

How can I insulate these exterior walls? Is this something a noob like me can do? I called an energy assessment company and they wanted $8000 to re-insulate walls and attic!!

I will answer all questions from experts here and hopefully can do some of this myself with out spending a ton of money (which I don't have)


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## Bud9051 (Nov 11, 2015)

Hi Tinker and welcome to the forum.

Best to start a new thread and add a link to it from your post here. You will get a better response on a new thread as opposed to one that is several years old.

Bud


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## NotYerUncleBob2 (Dec 29, 2017)

TinkerDude said:


> I just discovered this thread and am adding to this in the hope of re-starting this discussion.


Usually better to start a new thread, but we're here and I already read it so...



TinkerDude said:


> We bought a 50-year old house in Boston and got a taste of leaking air/cold bedrooms/leaky window/leaky attic doors when it got really cold.


Welcome to the joys of owning a charming old home!



TinkerDude said:


> I have been attacking simple problems like re-sealing entry doors etc, using rope caulk to seal gaps but I am discovering that some walls have zero or no insulation.


That's a great place to start as you're losing a lot of heat through those gaps. It's fairly common to find little or no insulation in old homes. 



TinkerDude said:


> How can I insulate these exterior walls?


The approaches will vary and depend on a lot of factors like what type of siding you have, what kind of wiring, what kind of structure, and whether you're doing other work already. A common approach is "drill and fill" where you pull a piece of siding, drill a hole in the sheathing and fill in with densely packed cellulose, then replace the siding for that spot. 


TinkerDude said:


> Is this something a noob like me can do?


Maybe. It's not an easy task and there's some equipment and skill involved. You'd also have to make sure that you don't have knob and tube wiring in those wall cavities since adding insulation against that type of wiring can create a fire hazard.
Insulating the attic is fairly easy though. Make sure you don't have knob and tube, then get in there and seal up any leaks from the ceiling so you're not losing your heated air to the attic, check to see where your roof is getting it's venting and make sure you don't cover that (see soffit vent baffle) then get some cellulose and a blower from your local big box and go to town!


TinkerDude said:


> I called an energy assessment company and they wanted $8000 to re-insulate walls and attic!!


That doesn't sound too far off the mark for a good sized old house with no insulation. 

I'd say that your first line of attack would be air sealing. Find the big gaps where you have drafts. Around windows, doors, attic access, outlets, old chimneys that aren't in use anymore, anything that doesn't have a good seal. Cutting down on the air infiltration will go a long way to making the house more comfortable. It's also pretty cheap to do. It's just caulk, foam, and time.


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