Insulating a metal building

[47WDXPW]

I have a sheet metal covered 30'x48' building with bar joists and girts and purlins tying them together. The floor is concrete with a vapor barrier and nothing else. The roof has a thin insulation that was rolled out before the roof panels were applied. There is no other insulation. I would like to use the building for storage and would like to control the humidity to the point to be able to store a restored car without damage in the long term. I have separate space to use to work in that is heated so this one will not need to be heated for a working environment just to control humidity. Currently there are no building vents. Im looking for ideas as to where to start, thanks Paul.

 

[47WDXPW]

Would a spray type insulation be easiest ?

 

[73RR]

Spray foam is the easiest but not the cheapest, based solely on $/bd-ft. Count all of the benefits it provides and you'll be happy. Properly applied, there is no air movement through the roof/walls of a sprayed structure (unless the building is moving around a lot) so the dew point can be controlled easier.

 

[47WDXPW]

73RR, with the spray foam will there still be the need to finish the walls as in sheet rock ?

 

[PeterT]

I sprayed the walls with about 1.5" of foam, then framed out 2x6 walls inside, hung r30 batts, then put up OSB & painted it was a fun project

 

[lakeroadster]

73RR, with the spray foam will there still be the need to finish the walls as in sheet rock ?

You'll need to cover the spray foam. It is a fire hazard and will degrade if exposed to UV.

How you cover it is your option. Sheet rock isn't the only option.

 

[readhead]

Spray foam is turning out to be a problem in metal buildings. It works great but we are seeing rust through on the sheeting and components and it makes repairs almost impossible if panels get damaged. Most companies are voiding warranties if a building is spray foamed. Foam should be covered as John mentioned.

Blanket insulation installed during erection would have been the best method but it sounds like you are past that. You still have some options for installing blanket insulation. Contact a metal building insulation supply company and they can give you some options.

Andy

 

[MrSurly]

Spray foam is turning out to be a problem in metal buildings. It works great but we are seeing rust through on the sheeting and components and it makes repairs almost impossible if panels get damaged. Most companies are voiding warranties if a building is spray foamed. Foam should be covered as John mentioned.

Blanket insulation installed during erection would have been the best method but it sounds like you are past that. You still have some options for installing blanket insulation. Contact a metal building insulation supply company and they can give you some options.

Andy

I'm new here, and am building my shop right now with plans to spray foam. I'm very interested in the topic and I would like to view info relating to this statement: "Most companies are voiding warranties if a building is spray foamed".
I have asked every supplier I have come across and so far, I haven't seen this.

 

[HunterDan]

I have one room off of my main barn (attached to, but I'm closing off) that I will be using for hunting related equipment/dressing to go out hunting and I want it to be as scent free as possible. So I am planning on putting 1/2" xps foam board on the inside of the purlins, then having it spray foamed ontop of that. That way no foam is on the metal, incase I ever need to replace

 

[johnnyradiant]

I'm new here, and am building my shop right now with plans to spray foam. I'm very interested in the topic and I would like to view info relating to this statement: "Most companies are voiding warranties if a building is spray foamed".
I have asked every supplier I have come across and so far, I haven't seen this.

I recall reading and talking to someone about this almost a year ago now - where there were some issues arising but that's all I can recall. My suggestion to make sure your building is covered would be to write to them about spray foam and get them to respond in writing. Then even if they change their policy later you will have the documented correspondence green lighting your project. Perhaps it is an insulation issue or maybe and installation issue that is arising. May be it only just a rampant wives tale.

 

[My Old Tools]

My builder just talked me out of foam. He said the screws back out worse and rust is an issue. I went with strapping and R32 bats in the roof as well as the 3" full wrap before the sheets go on.

 

[73RR]

UV is an issue and most permitting jurisdictions will require covering the foam for fire protection. 'Covering' can be a hard cover such as sheetrock or OSB or a protective spray coating provided by some 'paint-like' products.
As to the rust complaints, if the building is properly constructed then why would there be any more issues with water infiltration with foam than with any other insulation. Yes, foam adheres to just about everything including the back of the metal sheeting so a layer of 'something' (15lb felt?) could be used if you need/want.
The biggest benefit to foam is that it seals the building as no other insulation can do. It fills every nook and cranny and stops air movement. Too much air moving in/out will kill your heating/cooling efficiency.

 

[73RR]

My builder just talked me out of foam. He said the screws back out worse and rust is an issue. I went with strapping and R32 bats in the roof as well as the 3" full wrap before the sheets go on.

How is it possible that foam somehow affects the screws? Screws go into the wood/metal structure, not the foam....foam does not move/expand/contract so it actually adds rigidity to the structure that should actually help reduce the sheet movement against the screws.
Batt insulation does a good job but unless there is a complete vapor barrier in place the rated R value is considerably less than the listed 'number'.

 

[joe--h]

Spray foam is turning out to be a problem in metal buildings. It works great but we are seeing rust through on the sheeting and components and it makes repairs almost impossible if panels get damaged. Most companies are voiding warranties if a building is spray foamed. Foam should be covered as John mentioned.

What causes the rust? Water vapor moving through the foam? Open cell or closed cell?

Joe H

 

[matt_i]

I would like to use the building for storage and would like to control the humidity to the point to be able to store a restored car without damage in the long term.

Imo easiest solution is to get some large dessicant packs, and then "bag" the car when not in use.

A graphic of the idea...
https://www.autopyjama.com/permabag-engl/cars/

 

[lakeroadster]

How is it possible that foam somehow affects the screws?

Perhaps....

A) Many of the screws go into the formed "high ridges" in the steel. The foam gets into these ridges and pushes out as it expands. This would apply pressure to the screws becasue the foam is trying to push the steel away from the boards when the foam expands in these ridges.

Screws that aren't installed in good solid wood, or screws that have the wood stripped by over zealous use of battery powered drill drivers, would be more subject to this.

Imo easiest solution is to get some large dessicant packs, and then "bag" the car when not in use.

A graphic of the idea...
https://www.autopyjama.com/permabag-engl/cars/

I did this to my '72 Nova and '31 Model A when I lived in Ohio. It's a bit tedious bagging the vehicle and is more suited for long term "over the winter storage".

It does a good job though of keeping the vehicle(s) dry.

 

[My Old Tools]

Glueing the sheets together into one virtually continuous sheet causes much higher stresses on the screws in some areas than letting sheets expand and contract individually. Makes sense to me just as wider planks expand and contract more than narrow ones. This works the screw holes and loosens the screws. The screw holes end up over sized. That's the story anyway.