Shop insulation and wall covering

[Boondox]

I'm getting ready to rebuild my shop by extending it 9 feet in length, bumping the 7' ceiling up a foot and installing a loft for lumber storage, and changing the roofline from 2/12 to a snow-shedding pitch. I'm biting the bullet and having the roof insulated with blown-in foam, but will be doing the walls myself with fiberglass (probably). Right now the walls are made with 2x4 studs. I was thinking of adding 2x2s on the inside wall to give me the extra room for insulation and wiring. Living in northern Vermont, it gets a bit chilly in winter. But like all structures, most of my heat loss is thru the roof, so I want to make sure that's done right. But is it okay to make a wall thicker like that? Not for load bearing, just to give room for wires and more insulation..?

Also, It's a shop. Doesn't have to be pretty on the inside. I was going to drywall it, but it seems wood would be a better choice for durability and ease of hanging stuff. All advice is appreciated

Pete

[JazzDad]

Hello Pete. I can't see anything wrong with your idea of adding some 2X2's for the additional depth. As you know, compressing fiberglass insulation is detrimental to its ability to retard the heat transfer. Another thought; is the building sealed tightly against the wind?

[Boondox]

</font><blockquote><font class="small">In reply to:</font><hr />
is the building sealed tightly against the wind?

[/ QUOTE ]

It is now! The snow is up to the bottom of the windows! [img]/forums/images/icons/grin.gif[/img] Actually, without snow on the ground it leaks air like a sieve, but that's about to change.

Pete

way south of you here in Mass/Ct, sistering 2 X 2's is common place for that exact reason. I jsut got some high density ( fits 2 X 6) walls, R24 that was on sale. Go for it!! I also use spray can foam in each bay to also help seal where the original 2 X 4's meet the outside walls. I've seen guys use the same glue they use laying new plywood floors down and it does the thing as the foam

[jtd]

Boondox, although I live in a considerably warmer climet, I'll also be insulating my shop early next year. I looked into plywood sheathing, but it's considerably more expensive than drywall right now. If you go with wood, you'll want it somewhat smooth to paint it for light reflection plus the smoother surface will not collect fine wood dust. I found this to be a problem in my last shop where I hung T-111 on the walls. Wood is more durable if you're somewhat clumsly like me and it does make it easier to hang things, but I consider these to be small tradeoffs for the cost difference. I'll be hanging greenboard at the base of the walls and around the doors and the rollup doors for better durability.

[RobS]

Here's a thought Pete, but I'll warn you I have not tried this nor do I have any idea if it would work...

Insulate your 2X4 walls as normal then put up 2" styrofoam sheets over the whole thing. Mark ahead of time for stud locations. On top of the styro, put plywood with long screws going through the styro and into the studs.

I have no idea if this would be cheaper or easier but it's something else to noodle over that cup of coffee [img]/forums/images/icons/smile.gif[/img]

[Pat]

Air infiltration is about as important as insulation. Insulation is good but with a leaky envelope you'll never get good performance. It would be a good idea befor insulating the walls while the cavities are all still open to caulk everything that can leak air. Ceiling insulation is probably a better bet than insulating the underside of the roof (if they aren't the same thing.) Foaming the underside of a roof can promote rot. Some shingle manufacturer's waranty is void if the roof deck isn't ventilated.

There are products for maintaining ventilation of the roof deck. Wind Chutes is one. They are innexpensive thin styrofoam pieces that go between rafters. You insulate below them and air circulates above them. They add a tad of R-Value but that is not their purpose. There are also similar products made with cardboard, aluminized on one side to reflect IR.

Make sure all penetrations for electricity, gas, water, etc are caulked. Lots of trades bore a series of large holes in studs etc. to pass wires, pipes, etc. The holes are often much larger than what is passed through them and consequently they can leak air. Caulk them. Check with a wet finger around light switches and outlets for drafts. Spray foam or caulk.

Caulk around the edges of the sill (bottom horizontal 2x4 in stud wall). There is a foam plastic in rolls, sill seal, for sealing under those boards in new construction. It should be at least doubled to get a goot seal. It can be cut to size to form a gasket to seal switch covers, and wall outlet cover plates. Much cheaper than the product sold precut for this purpose.

Light a stick of incense or a cigarette and slowly move it such that the smoke column goes up the edges of the window frames and look for drafts to caulk.

You can use 2x4 or even 2x6 added on to your walls to give a deeper cavity for more insualtion B U T you want to stagger the studs not attach them to the existing studs. Studs have a much lower R-value than the insulaltion and heat will leak through them. Studs really lower the effective R-Value of a wall as does windows. If yo use 2x4 added on yoU have room for a thicker batt of F/G than with 2x6. The staggered studs are a bit more of a challenge to insulate. Oh by the way... You don't have to have the new stud wall in contact with the old stud wall and it is better if yoU don't. You just need some spacers at the top and bottom for support.

2x2's spaced out from the original stud walls with spacers about every 2-3 feet of stud height will work fine. With the internal wall spaced out from the external wall it is OK to line up the studs for ease of installing DEEP batting. Just fluff it up a little so it fills the space between the studs pretty well. The thermal break between the studs will help performance and it is free. If for some reason (warped clapboard construction or whatever) you cant stop the air infiltration very well, you can add a layer of house wrap between the old and new stud walls. It will breath but not support a strong draft. This will require two layers of batts, more hassle. If you want to add new studs directly over the old studs, place styrofoam strips cut from sheet between the new and old studs to form a thermal break. An inch thick thermal spacer should do fine and gives an extra inch of cavity depth for more insulation.

One final thing... Peg board is a wonderful thing in a shop but don't use it for the interior walls over fiberglass. F/G dust WILL come out through the holes and you will breathe it! Cover the walls with drywall or whatever then hang up peg boards.

Sorry this wasn't better organized. I was just coming off the top of my head.

[img]/forums/images/icons/smile.gif[/img] Pat [img]/forums/images/icons/smile.gif[/img]

[Boondox]

Some great points to consider! Thanks [img]/forums/images/icons/smile.gif[/img]

Pete

[em14]

Boondox,
There is an interesting and fact filled article in "Fine Home Building" about insulation. I would recommend reading this ... it's not a long article but well done.
Leo

[Stoneheartfarm]

Saw one where they insulated using fiberglass, then ran 2x4's perpendicular to the studs and filled in between with EPS foam. This provided a thermal break between the studs and the drywall, with only small areas where the studs actually touched both the outside sheathing and the drywall.

If I recall right, wood is about R1 per inch, so a 2x4 is about 3.5. Adding a thermal break boosts it considerably.

Steve