My Florida metal building and spray foam with mini-split

[ryanx1776]

I have designed a 30x55x16 metal building pictured here. I am wondering two things:

1- What would you recommend for spray foam in Florida on walls and ceilings? (depth and type)
2- After spray foaming it- might I be able to expect a 3 ton mini-split to keep it comfortable? I'm not talking 68...just NOT blazing!

EDIT: Building is up!

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[chinboys]

Have a or get a Manual J calculation done based on your usage, location, building materials, and insulation ratings.
Get a blower door test done to see how many air exchanges per hour the building is getting.
Install a big ceiling fan or make sure the vents are high enough or the indoor evaporator unit install height is set high enough as cold air sinks and hot air rises.

Heat removal via HVAC is accomplished by first removing the latent heat. Your money or cost to operate an AC is primarily used to remove the humidity from the air before the lowering of the temperature can occur (sensible heat removal).
This means you need to prevent humidity from entering as much as possible if you want your AC to create a 20-25 degree delta in temperature between the outside and inside of your garage.

Too small a unit and you will never get humidity or cooling relief.
Too large a unit... the new minisplit units have variable frequency drive compressors and will adjust according to the load but you want a system that is running at or near or slightly above its cooling capacity.

 

[ryanx1776]

Have a or get a Manual J calculation done based on your usage, location, building materials, and insulation ratings.
Get a blower door test done to see how many air exchanges per hour the building is getting.
Install a big ceiling fan or make sure the vents are high enough or the indoor evaporator unit install height is set high enough as cold air sinks and hot air rises.

Heat removal via HVAC is accomplished by first removing the latent heat. Your money or cost to operate an AC is primarily used to remove the humidity from the air before the lowering of the temperature can occur (sensible heat removal).
This means you need to prevent humidity from entering as much as possible if you want your AC to create a 20-25 degree delta in temperature between the outside and inside of your garage.

Too small a unit and you will never get humidity or cooling relief.
Too large a unit... the new minisplit units have variable frequency drive compressors and will adjust according to the load but you want a system that is running at or near or slightly above its cooling capacity.

thank you for the reply. valuable insight!

 

[chinboys]

thank you for the reply. valuable insight!

If you are handy with electrical and HVAC work... buy a Mr.Cool DYI system for a self-install.

 

[FL Guy]

I’m in Florida also. Building is almost 1000sf with 12’ walls.
I have foam on ceiling and walls. I installed a 36k btu mini split and have no issues keeping the garage at 70°.
Building gets full sun from 11-7

 

[ryanx1776]

I’m in Florida also. Building is almost 1000sf with 12’ walls.
I have foam on ceiling and walls. I installed a 36k btu mini split and have no issues keeping the garage at 70°.
Building gets full sun from 11-7

Appreciate the reply. did you go with open or closed cell? I'm now considering two (2 ton) minisplits. One on either end of the building.

 

[FL Guy]

Appreciate the reply. did you go with open or closed cell? I'm now considering two (2 ton) minisplits. One on either end of the building.

Closed cell.
Here's my topic on it. I am happy with it. Its a garage after all.

Got me some Spray Foam..... What a mess!

Got my building spray foamed yesterday. I paid for 2" everywhere, but this crew no doubt gave me much much more than that. The tubing is 2.5". 90% of the foam comes past it about 1 - 1.5" easily. The roof is packed full of foam! Same 2.5" tubing, + 1" for the purlin.. No doubt there is minimum...

www.garagejournal.com

 

[TheEquineFencer]

I just another thread from a couple of guys that had their metal buildings sprayed. If it gets behind the ribs, it'll push the metal out and distort the siding. Here's the link!

Barn Siding Looks Distorted After Spray Foam

I just had my 42x63 Pole Barn spray foamed with 3" of closed cell on the walls and 8" of open cell on the metal ceiling. After the job was done the foam seemed to push off itself and distort the metal siding. You can really see it along the horizontal 2x4's where the siding screws too. Seems...

www.garagejournal.com