Welcome to the DoItYourself Forums!

To post questions, help other DIYers and reduce advertising (like the one on your left), join our DIY community. It's free!

Cardboard walls?!


Pete HL's Avatar
Member

Join Date: May 2014
Posts: 11
ME

05-07-14, 06:33 PM   #1  
Cardboard walls?!

The amount of heating that I had to do this past winter to keep my house warm was too much, so I want to replace insulation in the walls. The house is a mobile home aka trailer.

Not all of the walls, but some have a sheet of cardboard (!) between the vinyl siding and the studs. Yes, it is more substantial than say the corrugated cardboard of a shipping carton, but you can easily push a nail thru it with your hand.

I'm getting at the existing fiberglass insulation in the wall by taking down the drywall panels from the inside of the house. My question is if putting a strip of plywood between the studs up against the cardboard sheet would help to increase the insulation factor to an extent that makes that additional work worthwhile.

Thanks in advance if you can answer this for me,
Pete

PS: This is all fairly new to me.

 
Sponsored Links
calvert's Avatar
Member

Join Date: Jan 2014
Posts: 466
PA

05-07-14, 07:20 PM   #2  
The simple answer is no. The "cardboard" is a version of "thermoply" which is designed to fulfill the basic function of sheathing .... to provide racking strength.

I can't see trying to enhance thermal performance with plywood. If your budget can handle it I would have sprayed, closed cell foam installed between the framing.

If you have to do the project in a piecemeal approach then you could install rigid foam board between studs and then back that up with fiberglass or rock wool if you can't afford to fill the entire cavity with foam. You have to be sure to seal the edges of the foam to the framing. There are several ways to do it, just review some of the posting that have been previously made.

 
Bud9051's Avatar
Member

Join Date: Oct 2008
Posts: 9,765
ME

05-08-14, 02:14 AM   #3  
How deep are the studs, 3.5" or 5.5"? If a standard depth, I would consider Roxul. Compared to fiberglass it would be a Cadillac. Then, if there is room, add a layer of rigid insulation over the inside of the entire wall. They make extensions for electrical boxes and you can extend the window frame for the trim. Then your vapor barrier. I grew up in a mobile home, but have never worked on them so methods may be different.

A key to decreasing the heat loss is to decrease the air leakage, so seal all penetrations you find. In some cases you may need a fire rated sealant.

One caution, if your furnace is burning air from inside your home, your improvements can become too tight such that exhaust fans like in kitchen and bathrooms may backdraft the exhaust gases. Any energy auditor can do a quick CAZ (Combustion Appliance Zone) test to be sure you are fine.

Bud

 
Pete HL's Avatar
Member

Join Date: May 2014
Posts: 11
ME

05-08-14, 04:48 PM   #4  
Calvert,

Thanks for identifying my cardboard as thermoply. I assume that real wood sheathing would be preferable, but at least nobody is saying they are appalled that this how the wall was constructed. That's a relief.

I kind of was thinking that probably the strip of plywood wouldn't improve thermal loss through the wall much or at all. Thanks for your opinion that the plywood wouldn't "enhance thermal performance". That was primarily what I wanted to find out. Installing the plywood strips would significantly increase the labor and cost of the project.

The studs in my wall are 3-1/2" deep. So my plan was to install 3-1/2" thick fiberglass with a paper facing (R-13). Hopefully better insulating than that is not strictly needed.

Bud9051,

Thanks for your suggestions. I've got 3-1/2" studs in the wall. I really do hope that I don't need to insulate as extensively as you propose. My heating system is a traditional wood stove burning 16" logs. I can live with burning 3 cord per heating season, but this past heating season needed more than that. I'm not too keen on working the entire summer making the improvements, so hopefully some improvement of trapping the heat in will be sufficient.

I always crack a window open in the room where the wood stove sits.

Thanks again & Regards,
Pete

 
calvert's Avatar
Member

Join Date: Jan 2014
Posts: 466
PA

05-08-14, 07:19 PM   #5  
Pete, you are welcome. Just a few things else to consider. As Bud stated, it is a good idea to check out the air leakage potential of the structure.

Actually, if you are going to just install fiberglass I would perhaps check out the stud cavities where the sheathing is stapled on. By that, I mean check the perimeter of each cavity that you expose and it may be a good idea to run a bead of foam or good caulk along the interface of the stud and sheathing to seal air leakage points. Also good to look at the floor assembly and make sure any holes around pipes, wires,etc....are sealed with a foam or caulk used as a fire/draft sealant.

Finally, as you are using a wood burner for heat, please make sure you have the proper clearances and fire resistive materials incorporated into the installation of that unit and have a few fire extinguishers handy.

 
Pete HL's Avatar
Member

Join Date: May 2014
Posts: 11
ME

05-09-14, 04:58 PM   #6  
Calvert,

Thanks for the additional advice. Will attempt to determine whether or not the sheathing has been firmly attached to the studs to prevent air leaks. Running a bead of caulk or foam at the joint between sheathing and stud is more work, so I'd like to forgo that if possible, but I'll have to try to judge if that is needed.

When I installed the wood stove in 2009 I was careful about clearance and I built a good hearth underneath, including several layers of concrete board. There is one fire extinguisher in the house. More might be helpful as I understand that a trailer gets engulfed in flames very quickly.

Regards,
Pete

 
Pete HL's Avatar
Member

Join Date: May 2014
Posts: 11
ME

06-03-14, 05:25 PM   #7  
structurally sound wall?

From a dictionary, sheathing is "a layer of material applied to the outer frame of a building to strengthen the structure and serve as a base for an exterior weatherproof cladding."

The thermoply isn't providing any rigidity to the wall, so I would say that several of the walls of my house are structurally deficient.

 
calvert's Avatar
Member

Join Date: Jan 2014
Posts: 466
PA

06-03-14, 07:37 PM   #8  
Pete, the material does strengthen the structure by providing racking strength. In essence this means that a row of studs in a wall won't all just twist in the same direction and collapse like a run of dominoes. It has been tested and rated as a sheathing with regard to that function. It does provide the functions of other sheathing materials, namely, air barrier and water resistive barrier EXCEPT that it is not considered a nail base material.

As with all sheathings, the proper installation of the material provides for the best service.

I'm not saying it would be my ideal choice but it has been used in millions of structures.

 
Search this Thread