Ridge Vent or No?

[mr_rayburn]

I have a 20x35 shop. It's red iron and sheet metal. I hired a company to spray foam closed cell the walls and ceiling. My plan has been to build-out the inside and install a 24k minisplit. I came home the day of the spray foam and found that I really liked the quality of work they had done, but the ridge vent was not spray foam / sealed. I asked the guy/owner about it and he said that his company does not seal the ridge vents because it will cause condensation, which will lead to issues. As he said, "I have seen customers have condensation issues and this is the solution." I politely told him a few things: 1- My previous shop, which was open-cell, was air conditioned 24/7 and had zero vents - completely sealed. I never had issues with condensation. We basically made a gentleman's agreement that I would wait a couple of months and see how it works.. If things were not up to my expectation, he would come back and close it. Well, this past week I have been heating the shop with the mini split and a propane heater. The shop is struggling to warm up and as soon as the heat is cut off... ****... its cold again. zero heat retention. I called him today and told him that I wanted to seal it up. He agreed to come do it, but insisted that I sign an agreement/contract releasing him from any damage or liability when it condensates and causes issues. I gladly agreed and am currently waiting on him to come perform the work. I have spoken with multiple people about this and have gotten a large variety of opinions and answers. I keep going back to "my last shop was sealed completely and ran the ac 24/7... never had an issue. Loved it" Now, I'm looking to get more info. I basically feel like having the ridge vent open is like having a window (or 2) wide open when trying to heat the building. Thanks for all input and I will answer all questions that I can!

 

[topcok88]

Mr_rayburn I feel you have enough experience with a previous spray foamed building and are educated enough to know that it must stay conditioned. But I can also sympathize with the installer as I’m positive it has caused issues with individuals who only condition when they are present in the building. I’ve seen it here and in FB where people seal and insulate a space and then only attempt to condition it when they are around - of course they will have issues. You’ll be fine as long as you condition the space 24/7.

 

[billconner]

How thick of spray foam and what climate or how cold for how long. Enough closed cell foam for the climate should prevent condensation.

 

[mr_rayburn]

How thick of spray foam and what climate or how cold for how long. Enough closed cell foam for the climate should prevent condensation.

It is single-layer spray. I'd say it's 1.25-1.5" thick. I am in SE Texas. We see 30-100 throughout the year. I think that was really got me concerned was when I ran the mini split heater and my propane heater and it just wouldn't heat up the shop. 24k mini split and a 36k but propane heater running for 3 hours. Outside was about 55. I couldn't get the inside of the shop over 66. Right in front of each heater, it was warm, but just ****.. gone.

 

[u2slow]

A ridge vent normally presumes you have 'cold' attic space and the ceiling is sealed and insulated. Air migrates in the eaves and out the ridge vent.

That's how my shop and house are done.

 

[Bretny]

They spray foamed the ceiling or the bottom of the roof? If the bottom of the roof is sprayed you close the ridge vent. If the ceiling is sprayed and theres attic space above the foam and below the roof, you leave it open.

 

[billconner]

Spray the vent. You should not get condensation in cold season with 1 1/2" of foam (and vapor barrier under slab). Inside of foam should not get to dew point.

Basically like a so called "hot roof". They're tricky because of "leaks" on inner surface but do work and yours seems more likely to be sealed.

Cant tell you how it will perform in hot time. I'd guess it will get warm. Not my climate.

 

[readhead]

Most sheet metal suppliers will not warrant their product if spray foam is installed directly to the siding. Most contractors,like myself, will not warrant a building if spray foam is installed.
Your spray foam contractor knows the problems associated with the product and has to weigh getting the work and dealing with lawsuits. He is trying to leave an out for the potential condensation but feels that if he seals the ridge that opportunity is gone and he has no choice but to not provide a warranty.
You are potentially trading comfort now for damage several years down the road and he knows it. The building is already sprayed so nothing can be done now. Sign the waiver, spray the ridge and enjoy your new shop.