insulation

[mike1091]

Hello everyone Im new to the garage journal and have a question on insulating my shop. Its 2X4's on edge on top of the trusses and it sweats a lot so I dont think I could put regular fiberglass insulation in between the 2X4's because its just going to soak up the condensation. One guy said I could use the 4X8 insulation boards and nail them to the bottom of the 2X4's but theyre about $20 a sheet if you get the 2 inch thick ones and that would add up pretty quick. so I was wondering what you guys all thought? I appreciate the input!

 

[carpenter383]

If you put a ceiling in with insulation of any kind on top it should stop most if not all of the sweating.
If that's not an option then spray in foam insulation is very good. It can be sprayed directly on the metal roof. It should stop the sweating, plus it will add strength to the roof structure.

 

[36tbird]

I had the same type of roof on my house as yours except the tin was screwed to 1X4 slats attached to the trusses. I had a roofing contractor come in and lift off the tin and plank it with the foil coated OSB because I did this to a house I was remodeling and was amazed at how during our south Texas summers it was pleasant when I walked into it. After the contractor put on the felt, we recycled the tin by putting it back down. I don't have an actual quantitative value for you, but we have seen a significant savings in our heating and cooling bills. I thought that the cost of the job was reasonable at about $2900 for the 22X40 house and that included the OSB and a solar tube.

 

[mike1091]

Ok thanks Ill look into that also.

 

[mike1091]

Spray foam would probably be my best option but its pretty expensive. I was wondering if i just put insulation between the 2X4's first and then put like tyvek or plastic sheeting over the insulation if that would work?

 

[mike1091]

What I was trying to describe was something like the wall to the right of this drawing but on my ceiling

 

[taskins]

If you plan on keeping this house, go spray foam. You will not regret it.

 

[mike1091]

Its just a pole barn but thats what most people have been saying.

 

[trialsguy]

a little bit of a hijack but I think I have seen where you can rent the spray foam machines and do it yourself is this recommended and would there be any savings to doing it yourself?

 

[semi75]

The DIY spray foam kits usually add up to be more than or the same as hiring a contractor. I've been debating foam for 6 months or so now and I'm still not ready to take the plunge, at least not until it warms up a little.

On the other hand spray foam seems to be the best option on a case like yours, and mine. Many of the pole barn builders in my area use a fiberglass with a white vinyl backing turned toward the inside. The trick is they put the insulation on before putting down the metal. I wish I had done this to my roof at least but I was in a hurry, building it on weekends and never thought it would be more than farm implement storage.

 

[dlenkewich]

An experienced batt & poly installer in your area could do this up for you for cheaper then foam, and you wouldn't have to deal with the itch.

 

[creativecars]

I’ve been researching this for my shop and other projects. My problem with DIY kits is they are pricey, need to be over 75 degrees and it would require several kits. I got a few local bids and in my area they are almost 2X the cost of DIY, and it must be all cleaned out for them to come in.
I just found a person who recommended spraying cellulose with adhesive added to the mix, it will stick to the wall on the inside and provide a good seal against air leakage. Maybe not quite as good as spray foam, but much cheaper and he will allow me to do it in a couple of days instead of all at once.

 

[mike1091]

Ill talk to some guys and start getting quotes on foam spray guys and from others.

 

[dlenkewich]

I’ve been researching this for my shop and other projects. My problem with DIY kits is they are pricey, need to be over 75 degrees and it would require several kits. I got a few local bids and in my area they are almost 2X the cost of DIY, and it must be all cleaned out for them to come in.
I just found a person who recommended spraying cellulose with adhesive added to the mix, it will stick to the wall on the inside and provide a good seal against air leakage. Maybe not quite as good as spray foam, but much cheaper and he will allow me to do it in a couple of days instead of all at once.

You'll still need a vapour barrier with that sticky spray-on cellulose or fibre, don't know if you factored that into the cost.

 

[REAL HOT SCHITT]

HI FROM NEW ZEALAND.

WE USE CORROGATED IRON HERE FOR ROOFING....(ZINC COATED 0.7 MM CORROGATED SHEET IRON. PLEASE LOOK INTO ...... new zealand steel and tube ltd + corrogated iron, or just dial in ....corrogated iron + n.z, or email.... or .. otago long run iron in dunedin n.z phone book for advice.

PRIOR TO ROOFING U SHOULD RUN LENGTHS OF BALING TWINE (SYNTHETIC) OR 20 MM PACKAGE STRAPPING SPACED EVERY 1/2 METER HORZONTALLY ON LENGTH OF SHED...(THIS IS TO STOP PAPER SAGGING) THE TWINE TO B STAPLED ON TRUSS AND ENDS WIRE STAPLE TAUGHT).

A BUTUMUS TYPE OF BUILDING PAPER THE LENGTH OF BILDING IS THEN RUN 1. 1/2 FOOT OVER EACH END AND STAPLED TO HOLD. ( THIS RUN IS TO BE 2 INCHES INSIDE FROM IRON OVERHANG ABOVE GUTTER) .

THE SECOND AND SUCESSIVE RUNS ARE TO BE 6 INCH OVERLAP (FISH SCALING)

A RUN OF PAPER TO BE LAID UNDER RIDGECAP PRIOR TO PLACING IRON...(MAKE SURE PAPER IS TITENED OTHERWISE IT LOOKS TERRIBLE WHEN FINISHED).

THEN PLACE IRON ON WITH TEX SCREWS OR ROOFING NAILS.

NOTE; PAPER IS USED AS IF THERE IS DEW IT WILL BREATHE WITHOUT TRAPPING MOISTURE AND THE SWEATING ...HENCE RUST.

PERFORATED ALUMINIUM COATED BUTUMOUS PAPER CAN ALSO BE USED BUT NOT IN DOMESTIC HOUSES AS IT MAY NOT BREATH LIKE PAPER.

DO NOT SPRAY FOAM OR HAVE INSULATION TOUCHING ROOF MAKE SUR YOU HAVE AIRSPACE AND VENTS.

AFTER ROOFING THE CEILING CAN BE INSTALLED USING PLYWOOD OR GYPSUM. NOTE PUT A LAYER OF BATTS ABOVE.....THEN ENJOY.

GOOD LUCK

 

[BTI]

Some of the quotes I have received for spray foam have been cheaper than I could do it myself.
The OP was concerned about the cost of foam board at $20 a 4x8 sheet....
Spray foam will be out of his budget.
I would do one of the 2, Spray foam or Ridgid foam board at least 2" thick.
Preferably thicker.

BTI

 

[mike1091]

Haha well I guess Im just going to have to **** it up and pay for the spray foam. but I just wondered what do you guys think would happen with just fiberglass insulation with plastic sheeting vapor barrier on top of it?

 

[Dragster Racer]

I'm not sure I read anything that makes this different from insulating any metal building. The foam is great if you want to keep the ceiling open. If you want a ceiling in it, which keeps the heat down where you want it...put a ceiling in with vapor barrier above it. Then blow in on top of the ceiling. Your attic at this point needs to be vented properly to deal with the moisture. There should not be issues with condensation with a properly vented attic and a proper ceiling with insulation on top. I did osb for my ceiling, but if I did it over I would probably do corrigated internal sheets, with drywall being maybe my second choice. Maybe I missed something in this thread, but please don't think that you are limited to foam or foam board on the roof.

 

[socapots]

take a look at that drawing again...
3 scenarios.. right now you have a metal roof.. cold on the outside.. warm on the inside.
just like that wall with cold on one side and warm on the other..

why wouldnt it work if you have the vapor barrier in the right spot?? (edit: like the far left of the picture)Afterall the moisture is condensation right? or is it actually leaking through the roof?

id say put a ceiling up and insulate it like any other attic space.
make sure you have good ventalation so the outside is the same temp as the inside and you good to go..

 

[REAL HOT SCHITT]

Note; spray foam may lead to corrosion as it does not evacuate condesate as its not breathable.....the foam system was banned in vancouver d.c in recent years as houses were rotting from the core.
The stuff is a gr8t insulation medium and practical but fails long term.

 

[LuckyRugger]

I'm going to go with spray foam, make sure you go with closed cell not open cell where is can absorb water. I don't recall the brand I'm going with, but it's used in both residential and commercial applications and has been for many years without any problems. I got a quote from a local installer for $4,100 to do my barn, 1728 sqft of walls at 2" thick and 1280 sqft of ceiling at 1/2" thick (spraying the top side of my ceiling from the attic). I'm heating my barn, so the better the insulation the cheaper my utility bill will be, so it will pay for itself.

 

[sneezer41]

RHS, this is simply not true.

poorly built poorly ventilated houses will rot with spray foam, or any insulation for that matter. If a local gov't has banned it, it is because they do not understand how to build houses

 

[jumpingryan]

Mike, alot of the suggestions bring up spray foam, and it is the answer to alot of problems including yours....

The other is just as you have it on your picture.... build a wall underneath your roof.... and add insulation and a vapour barrier on the warm side..... flat roofs are done in the same manner, they have a few inches from the exterior roof sheathing and covering, and then the insulation and vapour barrier...... the trick is the air movement and venting. You need to ensure there is airflow from the soffits to the top roof vents.

It doesn't seem that you have too much roof structure to deal with, so that is an option (not the easiest one though, and sometimes your time IS money no matter if you are working or not). The big pain will be the angled ceiling, tying in a hanging wall, and making a continuous tied in vapour barrier, which ties into insulated vapour barrier on the walls.

I tend to agree with the guys, that closed cell spray foam would be the easiest (yet most expensive) option.... I don't believe it causes rot if it is properly applied to anything as per the other post, as wood will still breath on the other side..... it is more likely the rot was cause by the other side being saturated with moisture.... (which works against the whole system of spray foam and signifies poor exterior construction leading to misplaced blame on an insulating product).

Think of the foam as a foam cup, how much sweating do you see on the outside of a foam cup in the hot summer with cold water inside. Now fill a standard plastic cup/glass with cold water & ice.... and watch the sweating (and further think of the plastic cup as a vapour barrier with no insulation). The condensation exists on the warm side. That about sums up the uses and applications of spray foam in construction, and the reasoning for it. Spray foam is a vapour barrier & insulation all in one, with little gaps & holes in it.

Note that is applies to summer and winter weather..... in winter, the condensation is there, but is on the inside of the cup, inside your coffee where you can't see it.

The only possible problem with the spray foam solution on your structure may be expansion of the metal as it heats up on the outside, causing the foam to break its seal..... However an expert spray foam contractor may be able to suggest a solution (or mix of foam) that would work for your application.

Good luck!

 

[semi75]

I had never heard the Styrofoam cup analogy, that makes sense.

 

[james1savage]

id say put a ceiling up and insulate it like any other attic space. make sure you have good ventalation so the outside is the same temp as the inside and you good to go..

x2. Go to a local steel building insulation provider and ask them for stock they don't use anymore. You'll get a great deal on it, you'll most likely get the batts unfaced (like standard batt insulation). Also, you can get from them white faced vapour barrier. I am using this to create the vapour barrier at the underside of the trusses and then just laying my batts between the trusses on top of the vapour barrier.

If you don't want to sheet your ceiling you don't need to, the facing is white and very sturdy, and reflects light very well.

I suspect this option is way less expensive than spray.

 

[Cobra6]

I am going to use this ADO ProVent on my attic
http://www.adoproducts.com/provent.html

Then probably do something with foil like this guy (although he also has a good idea with the foam - saves a little money, too)

 

[dirttracker18]

+ 2 on the ceiling idea to save money, spray foam is best but very expensive.

Just be sure you resolve the moisture issue by venting at both the soffit and at the roof peak or as close to it as possible. Vents on one side only or they will vent to each other instead of from the bottom up like it should.