Dealing w Texas Heat

[bluegoose972]

Here is my scenario....Constructive criticism would be appreciated.

Just had a 30'x35'x12' tall weld up metal building installed. Going to install 1" closed foam on the walls and 2" on the ceiling, at the recommendation of the foam contractor. Then going to install studs on walls at 2 ft spacing and cover walls with OSB.

The shop will have a 24" exhaust fan at the peak in the ceiling for pulling hot air out and will also have three ceiling fans for air movement.

I could add AC units, but feel they will just be a waste as the door is not insulated and most of the time, I will probably have one of the roll up doors open. Plus, the budget isn't allowing AC units right now.

1) Is 1" and 2" enough closed cell insulation? The stuff is expensive and not sure that I would get enough bang for my buck to increase the thickness.
2) Reading varying reports on fiberglass insulation between the OSB and Closed Cell....Should I just leave as open air?
3) Exhaust fan a good idea? Was recommended by the spray foam guy and we had one in CA...Made a huge difference in the evenings when you could pull all the hot air out of your house.
4) If the doors are closed, could a mini-split or window unit(maybe two) be added down the road and have a chance of keeping it bearable inside? Bearable would by around 80 degrees when it's 100+ outside.

Really trying to get the best bang for the buck. No use spending a whole bunch of money on foam only to have the doors be the weak link. And if a couple of AC units can keep the temps reasonable with good air movement from the fans, then I'll be a happy camper.

 

[Marctrees]

You are covering the walls so there is absolutely no point in CC.

OC is what you should be using everywhere... much cheaper per R.

The OC will end result seal sufficiently to block infiltration.

Leave airspace behind OSB... and if you are considering "Flash and batt" forget it... just go w thicker OC and be done in one day.

Of course the exhaust fan is a great idea... run it only selective times when it will bring in cooler air.... like you said you did in CA.

The ceiling fans may not be as great as you imagine due to mixing all air in building vs leaving stratified... you would then be cooling ALL your cubic footage rather than letting your AC'd air lay lower where YOU are.

Your building should not have any sofitt or ridge venting if you will be AC'ing.

Overhead doors really need to be insulated, either from factory or DIY later.

You should be able to get 4" OC for approx ballpark $1.45/ sq ft.


We are doing an almost exact situation like yours.

Going 5" OC under roof, 4" in walls and gable ends.

We will be installing two 24k btu "Window" AC's in walls at diagonal corners... will give us fast temp drop... then run one closest to workbench area.

No ceiling fans as they would only bring warmer air up above into the mix.

Will be using like $50 portable fans where we will be working.. blowing more or less horizontally.

I dun studied this like crazy... pretty firm what I'm tellin you.

If you like PM me for any info.

edit - This sounds to be a workshop where you will be spending allota time, often w AC, not just a storage garage... SO, You definitely are way better off buying more R under the roof for sure, and secondarily the walls also.

There may be easier ways to attach OSB rather than full studding, depends how the building walls are built.

Marc

 

[Marctrees]

Guys will chime in talking all about Minisplit vs "Windowshaker"

That debate will go on forever... but has NOTHING to do w everything else you asked and I wrote about.

Already PLENTY of searchable threads on that.

That should be a separate discussion.

Marc

 

[strutaeng]

Here is my scenario....Constructive criticism would be appreciated.

Just had a 30'x35'x12' tall weld up metal building installed. Going to install 1" closed foam on the walls and 2" on the ceiling, at the recommendation of the foam contractor. Then going to install studs on walls at 2 ft spacing and cover walls with OSB.

The shop will have a 24" exhaust fan at the peak in the ceiling for pulling hot air out and will also have three ceiling fans for air movement.

I could add AC units, but feel they will just be a waste as the door is not insulated and most of the time, I will probably have one of the roll up doors open. Plus, the budget isn't allowing AC units right now.

1) Is 1" and 2" enough closed cell insulation? The stuff is expensive and not sure that I would get enough bang for my buck to increase the thickness.
2) Reading varying reports on fiberglass insulation between the OSB and Closed Cell....Should I just leave as open air?
3) Exhaust fan a good idea? Was recommended by the spray foam guy and we had one in CA...Made a huge difference in the evenings when you could pull all the hot air out of your house.
4) If the doors are closed, could a mini-split or window unit(maybe two) be added down the road and have a chance of keeping it bearable inside? Bearable would by around 80 degrees when it's 100+ outside.

Really trying to get the best bang for the buck. No use spending a whole bunch of money on foam only to have the doors be the weak link. And if a couple of AC units can keep the temps reasonable with good air movement from the fans, then I'll be a happy camper.

1) Is R5-R6 good enough for walls?
2)Are you reading information that states cavity insulation is not a good idea?
3) I'd say no attic vent if you want to condition the space and have no ceiling, unless you want to throw away your expensive conditioned air through the roof...
4) Yes

Bonus) Go to Greenbuilderadvisor.com and do some reading.

Hint) Read article on "Flash and batt"

 

[Marctrees]

Cavity insulation IS a good idea.

I, for myself, originally planned on flash and batt... then decided it made much better overall sense to just use more OC and no batt.

This was after I found OC cheaper than originally understood.

Job done in one day instead of playing w stretching strapping etc labor.

YMMV... F and B is fine, but I found more OC smartest.

Marc

 

[ddawg16]

Humidity is going to be a big issue.....don't be surprised if it rains inside at times.

 

[dcg9381]

Just had a 30'x35'x12' tall weld up metal building installed. Going to install 1" closed foam on the walls and 2" on the ceiling, at the recommendation of the foam contractor. Then going to install studs on walls at 2 ft spacing and cover walls with OSB.

I just did this. Bigger building. Same general geography. I used 3-4" of open cell instead (sheer economics). Framed in studs covered in OSB. I did not insulate between as I'm not going to frame the whole building.

The shop will have a 24" exhaust fan at the peak in the ceiling for pulling hot air out and will also have three ceiling fans for air movement.

If you don't have AC, this is fine. Alternate systems could be push/pull fans if you want to keep the doors closed. In fact, I'd encourage to you consider operation with the doors closed. My shop lights bring in all sorts of bugs at night if I leave a door open. Starting about 20 days ago, flies are out. If I leave a door open with the lights on, I have a BIG bug problem in about an hour. We're looking at a "air curtain" or maybe a screen on the door it's so bad...

I could add AC units, but feel they will just be a waste as the door is not insulated and most of the time, I will probably have one of the roll up doors open. Plus, the budget isn't allowing AC units right now.

I have 3 14'x14' doors. I think they are R5 roll-up. These suckers, even with weatherstrip.. well, I can see sunlight in the tracks.
That being said, the building is 2400sqft, with 16' sides and 2 x 24k ductless systems cool it well so far. Cost was $2300 or for my ductless splits, self-installed.

1) Is 1" and 2" enough closed cell insulation? The stuff is expensive and not sure that I would get enough bang for my buck to increase the thickness.

The economics of this depends on a number of things... More insulation is better, but there is a budget. If you're not using the shop all the time and not paying a ton to cool it, look at what you're trying to do.

2) Reading varying reports on fiberglass insulation between the OSB and Closed Cell....Should I just leave as open air?

I'm buying what they are selling in terms of "mixed" insulation - I'd do it. But realize the majority of heat gain loss is probably at the roof.

3) Exhaust fan a good idea? Was recommended by the spray foam guy and we had one in CA...Made a huge difference in the evenings when you could pull all the hot air out of your house.

With no AC, I'd say "required". Again, I'd do push-pull or come up with a system so you can keep the doors closed at night.

4) If the doors are closed, could a mini-split or window unit(maybe two) be added down the road and have a chance of keeping it bearable inside? Bearable would by around 80 degrees when it's 100+ outside.

See my indication above.

 

[Marctrees]

bluegoose - You may want to re think your statement below.

"No use spending a whole bunch of money on foam only to have the doors be the weak link."

I understand why you said this, but all told it is untrue.

Besides, one can always insulate the doors w foam sheet.

Marc

 

[Falcon67]

Guys will chime in talking all about Minisplit vs "Windowshaker"

In that size building in Belton, mmmm - really big window shaker if that would even work LOL. As above, spend as much $ on insulation as you can. Metal ( and concrete - read Hardi) heats up big time in the Texas sun. DIY insulation on the doors would also be called for - not expensive and surprisingly effective. Even just 1/2" foam makes a huge difference. Thicker if you can do it.

Keep that air moving helps also - as you seem to be doing.

If you were going to AC the place, my WAG would be somewhere between 2 and 3 tons depending on insulation.

 

[bluegoose972]

You can insulate roll up doors? I didn't know that. Will start researching that. I had no idea.

 

[matt_i]

In the buildings I've worked in (various, red iron, framed stick) if I can see the roof, eventually I can "feel" the radiant heat from the inside of the roof in the summer, even if the place has A/C.

The only effective way that I've seen, again seat-of-the-pants measuring, is to add a ceiling and force the radiation to happen twice, which it doesn't do very well.

After that, fans inside and replacing hot interior air with ambient air from outside are the only good choices.

I have seen a system of piping which mists or sprays a metal roof with water, to force evaporative cooling. Could work if cheap access to water. Possibly some long-term penalty to the roof life if its wet a large portion of the time. I've not been inside a building which used this but the idea makes sense.

 

[Marctrees]

I was thinking sectional not roll up.

Marc

 

[dcg9381]

Roll up doors - at least mine, tend to make a bit of noise when it is windy. The one thing I'd change about my original shop design is to move to a better-quality sectional door.

Note, both of my doors are protected by eves / shed roofs, so I don't have direct sunlight on them. My experience might be different if they were directly exposed.