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pretzels 03-24-2011 03:48 PM

New custom house, concerns/problems.

I recently and am still currently building/finishing out my DIY house. I have a few worries after seeing some potential issues...

First off, let me describe the house, as it is not the typical house and you will probably need this info to help me. Questions will be at the end.

The building/frame.

I designed and had a custom metal building built with 2 stories. So, basically we got a metal building with metal ibeams and 4x4 beams as most of the major framing, with a slab foundation, and, gavalume siding. The metal frame was welded, not bolted together. The second story is supported by more ibeams and metal perlins every 16 inches. It's more of a loft style second story.

Inside Framing for drywall hanging and interior walls

We then added 2x4 framing spaced 24" inside the building. This was added inside right up against exterior walls and attached to the metal frame. The interior walls are all 2x6s spaced 24" (did this to add more insulation for sound proofing.)


Then we wired and plumbed the building. romex wire, pex plumbing, pvc drain pipes. (network/com wiring installed later, not really important)


Insulation was then applied. Closed cell spray foam. 4" on Ceiling, 3" on exterior walls. We also then applied r-13 recycled cotton/blue jean batt insulation in the 2x4 walls, r-19 in the 2x6 interior walls and the ceiling. So basically we have the spray foam, then the batt insulation.

Walls and ceiling are drywall. 5/8"

Second floor has a 1 inch tongue and groove subfloor, its not osb or plywood, its the partical board. We have a hard wood flooring layed over the top of that, nailed down.

First floor is bare concrete slab.

Windows we have windows installed on every wall basically, lots of them. They are low e coated. They are just aluminum frame mill finish. They are all just drywalled around with no wood window sill. So basically drywall just goes up against the aluminum window frame. They are caulked around.

Part of the second floor (master bedroom) is actually jetted out the side of the house to become a carport for parking 2 cars under. So its subfloor is sprayed with closed cell spray foam underneath.

HVAC is a trane heat pump. I have exposed spiral metal ductwork.

There is no attic.

This is in Texas.

I think thats good enough info for now. Please ask questions to clear anything up.



The windows. After about only a year living in this house (still painting and working on things here and there of course) we have a major condensation problem. The windows basically sweat badly all winter long. They had about a 1/4 inch of ice on them this winter. This made puddles of water (crap loads) everyday on the drywall window sill. Caulk/paint is already messed up and a few days ago noticed a mold spot the size of a half dollar coin on a window sill.

Downstairs, we noticed the concrete slab was damp looking in one corner (exterior walls) and then we noticed that in another exterior wall corner upstairs in the master bedroom (the room above the carport.) The subfloor must be getting damp, causing the hardwood floor to start cupping a little and separating.

The metal duct work of course is 'leaking' in the summer time.

My thoughts on the condensation: (Should I freak out that there might be mold in the walls already)

-Dont know what to do about the windows.

-The corners with the dampness on the floors I think might be due to the fact that those corners had several 2x4s that might have blocked the spray from from completely covering the exterior sheet metal/beam in those corners.
(As in the spray foam installer couldnt get enough back there) Which would make that exposed metal (behind the drywall) condensate, then that condensation runs down to the floors.

-The exposed ductwork only really condensates in a hallway upstairs that doesnt really get air conditioning, and seems warmer than the rest of the house in the summer. Which would cause the condensation from the cold ductwork meeting that warm air.

The only thing i have read that would help with any of this condensation is:

My house is sealed to tightly, and needs ventilation. Problem since no attic. And would this really make a difference. I already have bath fans in the baths and laundry.

Any thoughts???

Pex/PVC pipe and Spray foam

I stumbled across stuff online that this is a bad combination. I am worried. The pex supply lines were run against external walls, and basically they got sprayed. They talk about temperatures reaching over 200F degrees with just one inch, and upwards of 300f degrees when its thicker. I did cover some of them with pipe insulation before hand, but, im still worried.

Welds/metal frame. Rusted

The buildings metal frame did have rust on it, before we finished it all out. It was mostly primed, but there were scratches and such that ended up having some rust, even around some welds. Do i need to be really worried about this rust getting out of hand breaking welds, and making it all fall apart soon? Am i just being overly worried?


Is it a typical practice to have drywall right up against a window frame, or is there always just a wood sill all the way around.?

This whole house has been an experience, a stressful one. I have been doing basically everything custom, because I am never happy with anything i find that is used in most houses. Its just a more modern slightly industrial look we are going for and basically you have to spend crap loads for some one else doing the custom work, trying to track down materials, or diy and trial and error. Plus, when you live far out in the middle of nowhere, you cant find any good contractors, and when you do, they dont care about quality. I havent been happy with anyones work, well, except the electrician, he actually cared.

I have some other things, but im at work and i have already wasted to much time....


oh'mike 03-24-2011 04:40 PM

This is not my area of expertise--You have the house to tight----Is there any fresh air exchange?

I think you need to get an expert in on this---

One member may have a suggestion--GBR---let's see what his says---Mike---

High Gear 03-24-2011 10:28 PM

Sounds like typical industrial building windows and they can frost on the north side.
I've seen double pane low -E even do this on industrial windows.

Do they have much of a "U" rating , metal frame and building skin probably conducting to much for the window.

Pick up a couple of these

Timers on bath fans.

Exhaust /hood fan for kitchen stove /microwave.

May need this one of these

pretzels 03-25-2011 08:50 AM

The windows are actually dual pane low e coating, with a blueish tint. I had to have them custom made because nobody sells windows like that with the mill finish (just the single panes) thinking i should have gotten some white or grey vinyl ones, the mill finish just looks good with the gavalume building though, thats why i wanted them.

At first I was thinking installing an inline dehumidifier in the hvac system or a ventilation system. I would have to find a place for them, and it would be a lot of work. I would have to build something to house the dehumidifier, or cut through the exterior walls or ceiling for vents.

i have that exact thermometer thing. That and we have a humidity reader on our hvac thermostat. It does read slightly high, but rarely.

And yes, we need to exhaust our propane cook top outside, we haven't done that yet. We were just going to get a recirculating one with the filters, but all this is happening. And the cooktop is on an island, so that will be some work too, plus i will have to find some way to hide all this, or have it exposed.

pyper 03-25-2011 09:46 AM

Do you have plastic under the slab to stop the moisture from coming up through?

pretzels 03-25-2011 10:21 AM

yes there was a thick black plastic laid down under the concrete slab

pyper 03-25-2011 12:17 PM

Well the plastic eliminates the easy answer...

Thinking about this some more -- the only way you can have ice on your windows is if they're cold enough to freeze. 32F, give or take.

Where do you live? It seems unusual that the inside of a double pane window would get so cold. How cold is it outside when that's happening?

You can buy a digital humidity reader at HD. These can be very useful. One thing to be aware of is that relative humidity will rise as temperature drops. So if you turn off the heat at night, the RH will spike.

Dehumidifiers are pretty expensive to run (it's basically an air conditioner and a heater that run simultaneously...). You might consider an air exchanger instead.

I wonder if you've got a hole in your roof or something in that corner with the bad flooring. With bath fans you'll eliminate your biggest source of moisture. Unless you're boiling pasta and steaming vegetables with every meal or something.

pretzels 03-28-2011 02:36 PM

Well the condensation is basically just when the outside is colder than inside. However the ice, was real bad this winter due to the 0 degree weather. Its mostly when its real cold. I have just never experienced this before in any shape or form. I live in the same area i have my whole life.

The worst windows are on the master bedroom, which is the north most walls, and the worst window, is the only one facing north with nothing blocking it outside from wind. So it gets the coldest.

I would think there might be a leak in the corner too, because there is a PEX pipe, (you know the ones i talked about before that got sprayed with the spray foam insulation,) but the corner downstairs that is getting dampish on the slab doesnt have pipes anywhere near it.

This stuff is so dramatic when you are basically in control of the building of your house.......i should have hired someone to blame it on. :)

Or just bought a double wide home and been done with it.

screwy 03-28-2011 02:54 PM

Check the humidity in the house, prolly high.

Your Slab floor has no thermal break from the outside? The edges of the slab are exposed? How thick and relative to the grade of the land is it above or below?

Do you have drainage around the Slab?

The metal structure of the house sits on concrete piers? Is the metal insulated? if so inside or outside?

Is your house air tight?

I would initially think that you are getting alot of moisture through the cement pad.

I have just built a barn, heated, with similiar characteristics to your house. My windows are dry but the metal will sweat.

pretzels 04-06-2011 11:28 AM


Originally Posted by screwy (Post 618677)
Check the humidity in the house, prolly high.

Your Slab floor has no thermal break from the outside? The edges of the slab are exposed? How thick and relative to the grade of the land is it above or below?

Do you have drainage around the Slab?

The metal structure of the house sits on concrete piers? Is the metal insulated? if so inside or outside?

Is your house air tight?

I would initially think that you are getting alot of moisture through the cement pad.

I have just built a barn, heated, with similiar characteristics to your house. My windows are dry but the metal will sweat.

no thermal break.

only about 2 - 4 inches are exposed, the whole concrete slab part thats the carport is exposed.

How thick and relative to the grade of the land is it above or below? what does this mean?

no drainage.

there are concrete piers, with concrete slab on top that has welding plates embedded in it, which the main metal ibeams for the building are welded to.

how do you insulate metal from the outside?

house is basically air tight except 4 bath exhaust fans and 3 sliding glass doors have little spaces for the tracks that allow air in/out.

screwy 04-06-2011 01:25 PM

I am no expert only learned from my experience and the homework that I have done.

My thoughts are that the concrete will take on moisture from the area exposed to outside.

No thermal break make me think that the slab will always be cold, in the past any concrete in our barn would "sweat" and give off moisture.

"How thick and relative to the grade of the land is it above or below? what does this mean?"- I was asking how thick the slab is? and where is the slab in relation to the grade(dirt)? Is the slab exposed can you see it from the outside or is the dirt covering it?

When we build our structure we used 8" x 8" box tubing and built the 2" x 6" walls on the outside of the box tubing, so the steel wasn't exposed to the outside. The walls are insulated.

I would think that the moisture is coming from the cement slab, what is the humidity of the air in the house? Run a dehumidifier and see if that helps.

We ran infloor heat in our slab and things are warm and dry, but I am farther North.

pyper 04-06-2011 01:59 PM


Originally Posted by screwy (Post 624689)

My thoughts are that the concrete will take on moisture from the area exposed to outside.

I'd be surprised to find out that the slab could take on so much moisture around the perimeter to give him a quarter inch of ice on the insides of his windows. I mean, there are plenty of slab-on-grade houses that don't have a moisture problem like this.

Also, I think something must be wrong with the windows. I've heard of single pane windows getting ice on the inside, but it would need to be pretty cold inside for a functioning double pane window to ice over.

I'm still voting for a leaky roof.

jklingel 04-07-2011 12:35 PM

Obviously, your humidity is too high. It must be brought down asap. Do you have an HRV? You should be bringing in/out 7.5 cfm/person, plus 1 cfm for every 100 sf of floor area. If no HRV, then bath/kitchen fans should be running a lot, with fresh air intakes opposite them. Don't get too worried about the heat loss; the heat capacity of air is small compared to all the water damage you may be experiencing. Double pane, low e windows, gas filled, etc, are good, but not if they are leaky, either the window itself or next to it. From your description, I can't see how you could have properly air sealed around the windows. That is a tedious and fussy job that should be done. Too, aluminum conducts heat like a mad man. I think that choice of frames was a mistake. Your slab edge is one of the most critical places in the house to insulate. I doubt that it is contributing to moisture, unless it is sitting against water, but you are pumping heat out there like crazy. You should have a minimum of 2" of rigid foam outside the edge and down 2'; 4" is not going to hurt you.

mustangmike3789 04-16-2011 10:21 AM

you said that the metal frame was mostly primed. did the welds have a protective coating over them or were they left exposed. scratches in metal is a great place for corrosion the start (look up cathodic prtection). bare metal will begin to corrode within minutes of being exposed to the enviroment. the primer placed on metal is normally a shop primer that will slow down corrosion during shipping and storage but it is not designed to last very long. this does not mean that your building is going to fall apart anytime soon. there are old railroad bridges that were built in the early 1900's that are still standing today that have never seen a drop of paint on them. those were also better,cleaner metal than those used today. due to the amount of moisture you have, you should try to protect as much of your structure as you can get to now that your house if finished. i would suggest an aluminum mastic over the welds, scatches and rust spots on the metal plus a good DTM or epoxy/eurathane coating. maybe im going a little overboard on this subject due to being in the protective coating industry but this is your investment.

Bud Cline 04-16-2011 10:38 AM

You could seek advice from someone that is totally familiar with that type of home and has been building them for forty years or more and they are right there in Texas. They may not talk to you tho because most everything you have described as your own DIY is in fact stolen from their home building concepts.:yes::whistling2:


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