I’ve got a question about concrete/concrete block structures and energy efficiency, or actually unconditioned comfort level.
Will be building a small 30 x 32 block lower level (totally concrete filled for hurricane strength), wood frame upper level house. Location is within 1/2 mile from the coast in the Florida panhandle.
The block lower level will be a woodshop and will be unconditioned. (I’ve lived here quite a while, so the heat and humidity doesn’t bother me as much). Also, it will be closed up most of the time with a dust collection system.
Can I expect a better comfort level than wood/fiberglass insul. walls unconditioned?
Will concrete be cooler in the summer and maybe too cold in the winter?
The reason I ask is I’m looking at the price of metal conduit/boxes/etc. and with the low price of lumber and drywall- well, you know.
Could run a small heater in the winter (coldest mornings in the 30’s) but I don’t want to try and cool the place.
House floor joists above will be R30 batt or spray foam, and the house is in full sun (may help heat in winter?)
Anybody know what I might expect? Thanks for your insight. Also wondering if concrete will be more soundproof.
Replies
The easy answer first ... more mass always controls sound better than less mass.
Florida ... hmm. Concrete mass can be OK uninsulated if routinely the daytime outside temp rises above AND falls below the desired space temp (say 60-65 deg). On those days, you would likely see a net energy zero and still maintain comfort. If summer temps routinely fall below say 70 deg at night, the mass will tend to cycle and store energy from the day and release at night.
Mass is generally no substitute for energy efficiency ... simply ... it doesn't insulate very well. That being said ... unless it is designed for e.g. passive solar gain, you should insulate it to maintain some level of comfort. But ... you aren't heating it. Best insulation is arguablly placed on the exterior, not the interior. If your winter daytime high temp is say >70, you may not have heating issues (i.e. uninsulated).
What provides the make up air for your dust collector ... or doesn't it vent outside?
In the Florida climate ... which is not my expertise ... you may not have big issues uninsulated. May have to think a bit more or wait for another to chime in here.
The dust collector doesn't vent outside.As for temps-Summer= 90's day (relentless for 3+ months), mid 70's to mid 80's at night.Winter= three to four cold weeks of 30's to 40's at night, but usually reaching at least mid 50's day. Other wise 50's night, 60's day.We don't get the temperature fluctuations here - the weather report is pretty much non-news.I guess I'm wondering also is would I block any (desirable)thermal mass by insulating interior of wall at R13, or is it better to have concrete interior and thermal mass without interruption.We are on a tight budget, so no ICF's or other costly measures (I think?) Basically get in the house and be comfortable enough. Hard to do woodwork in coveralls or with sweat dripping all over you work.
I think you will find arguments on both sides of the fence ... insulate outside vs. insulate inside. It is commonly thought the best is to insulate the outside and have the mass to the inside. But my studies on this go both ways. Insulate the inside and the mass works on the outside much the same way it works inside.
If it doesn't cool off much at night during the summer, it's best to insulate. In or out ... you need to control loss/gain. Mass alone won't do this (unless it is under the circumstances I indicated earlier).
Insulating outside (exposed) incurs the cost of weather durable finish. On the inside, gyp bd is relatively cheap. Is this smooth faced CMU? or are you going e.g. split face?
I would make my decision on the easiest or most acceptable in your particular situation - insulate one or the other. Energy wise you will benefit either way, I think.
Then ... plant some trees to shade like the other guy said. Lots of shade is always good.
I'm assuming this is an entirely above grade situation, right? Any windows in your shop?
Thanks everyone - lots to think about here.I know I don't want to insulate the exterior of the block. I guess I would rather put extra money in the upper level house. Planning on closed cell foam in 2 x 6 wall and bottom of truss roof (hot roof) but cool attic. Been talking to insulators here and that seems like the way to go.To be more specific on the lower level shop I'm planning on smooth face block, scratch coat stucco (mortar) with a white/off white paint or dryvit coat. Two 9' insulated overhead doors (south wall), windows on other walls, 6' french doors on north wall. The shop will be mainly closed up when I'm milling because of noise.Also I can completely shade the west wall with a trellis because that is the walkway to stairs to the upper level. It's a "garden" style house so that would go well. Maybe that will help keep it cooler.I guess my question boils down to this -I worked in a unconditioned pole barn shop here for a few years, which was real hot and real cold, so I hope concrete is better than that.Right now I'm in a unconditioned garage (south facing o.h.doors) with R-11 frame walls, attic above R-30 batt. Thats pretty hot/cold too.So, I'm wondering if concrete by itself will be any better.I have a small window a/c in the r-11 garage now, but it doesn't really help. Maybe a window a/c in a concrete shop will perform better.By the way - all walls and slab edge are above grade.
from shop point of view, insulate inside, put plywood on wall so you can hang stuff
We're finally getting somewhere. Sounds like the west side may be covered pretty well. My additional comments:
1) Extend that arbor/trellis to the south a bit to maximize its benefit.
2) elminate the windows on the east ... if you can. They are, by far, your biggest summer energy problem and do you little good in the winter. If you feel you can't eliminate them ... consider longer, narrower (e.g. sight height) and with an overhang (which doesn't do a lot, but a small one can help a little). At a minimum ... mirrored AND tinted glass (SHGC down at 0.15-0.20). If you can spare vegetation to shade the windows, that would be great. You really won't notice the mirror/tinting from inside ... you still have a view. On the outside consider the same upstairs on the east exposure.
3) on the south ... if you eliminate the windows on the east, consider putting that money into [untinted] glass in the garage doors. Commercial glass doors are fabulous ... albeit expensive (about double the cost, I think). This must be accompanied by an overhang/eave to protect the glass from the high summer sun. Doesn't require a deep overhang (2 ft will buy you a lot of affectiveness). A commercial door can be had with a variety of glass ... part clear, part translucent, etc. Even a standard door can be ordered w/ lots of glass, I think. The overhang does you well in summer and lets the heat in in winter. Both will offset your thermal issues well. (think about the same principles upstairs as well if you want to minimize your energy bills).
Food for thought. Hope your hungry
Yep - there's suddenly a lot to consider. I was just going to put up the block, run emt conduit, which to me would be nicer for future electric expansion, and get to c.o.I'm a builder (of small, simple houses) so I understand and respect the codes. Just want to get done with the county and do what I want to do with my own house as money comes. (not promoting that to anyone unless your going to follow code whether the county's watching or not!)I can see now that I really need to consider that south wall and glass in the overhead doors and with shading in the summer. I remember seeing the pictures in a book somewhere of solar energy (heat) going through the glass, bouncing off the floor, and absorbing into the surrounding walls. Not that it gets that cold here, but after you get used to summer in Florida, you acclimate (took me about 6 years), and we don't do cold anymore.I think the concrete walls will be cooler in the summer than frame walls. (remember - closed shop, except for airing out on cleanup day)
I can see now that I really need to consider that south wall and glass in the overhead doors and with shading in the summer. I remember seeing the pictures in a book somewhere of solar energy (heat) going through the glass, bouncing off the floor, and absorbing into the surrounding walls. Not that it gets that cold here, but after you get used to summer in Florida, you acclimate (took me about 6 years), and we don't do cold anymore.
Now you're thinking more ... that is good. Architecture 101 ... not complex, really. Some simple stuff. You can make a big [energy] difference w/ some simple changes while still making things functional/nice and not go broke doing it.
Also ... I've found that MOST of the time you don't have to worry too much about the aesthetic disparity of mirrored/tinted glass on one side of the house and clear on the other. I've done it on two houses ... you don't even notice it really inside or out.
Thanks Clewless1.....you need to change your screen name.
No ... I like it. Clewless ... not clueless ;)
It keeps people guessing ... Riversong would disagree strongly w/ you BTW.
but after you get used to summer in Florida, you acclimate I can work in 100 degree weather all day and not bother me. anything under 45 bothers me
There ya go! We're sissys, we admit it...you can keep the snow (but it's a dry cold!)
Edited 2/8/2009 9:23 pm ET by back2work
Attempting a picture....hmmm, 2MB....sounds big. oops
Edited 2/8/2009 10:10 pm ET by back2work
I thought you said the slab was integral w/ the wall/footing?
I'd skip the horizontal insulation. IMO it would be a waste for you. The vertical ... cut the insulation at 45 except for about 1/2" of the insulation edge ... to enable the slab to come very near the wall ... w/ the 1/2" used as a thermal break at the edge of the slab (between the top of the slab and the wall) ... that has been a standard in the NW. Another option is to use e.g. a 2x2 as your thermal break around the edge and on top of the vertical insulation. At the garage door ... allow it to just end under the slab; not perfect ... but what the hay.
Or you can go to the exterior ... again cut a 45 on the insulation. Have a sheet metal guy bend a piece of flashing and run under your stucco system.
Don't go overboard ... you're in Florida ... you want cold? go to Frostbite Falls and visit Bullwinkle!! Go up there once every winter ... it should serve you well to feel toasty in Florida. ; )
I see. Thanks
I'm going down another rabbit trail, if you all are still around.....Wondering if it would help things in this instance (unconditioned and all) to put rigid insulation under the slab and maybe leave the "middle" insulation out for geothermal benefits. I could also break the slab at the wall with insulation.The reason I ask is our house right now has a block/slab foundation, frame wall, with 2-3' of block above grade. Flooring is tile and boy is it a cold floor in the winter! Next to the exterior walls especially.The new garage/shop will be a floating slab actually about 2"-4" above the footing. Pretty much set up for insulation. I was going to dig down to the footing so the slab sets on it (thicken the slab), but insulation could go there just as well. This slab edge will be above grade also.Sorry this concept sounds new to me, but in the south we don't think about insulating slabs. Actually around here we're a little behind on some technologies. Don't mean to offend fellow southerners, just making an admission.
I lost you on your slab configuration. You can insulate the perimeter of the slab ... either inside or outside the foundation wall (although you hinted at a monolithic or 'thickened slab edge' type of pour, so I'm not really sure. The perimeter insulation would be vertical. Can't imagine that you might have cold feeling slabs in Florida. But I've never been there ... so not really in touch with it.
Where I'm from ... you do a foundation wall up to say 6-8 inches above grade and pour a slab inside that, at or below the top of the wall (most of the time finished slab level w/ the wall top). Not to often pour the slab over the top of the wall (except e.g. at garage doors).
Around here we do -
monolithic - footing and slab poured at the same time.Block and slab - top block is lintel with slab poured into block to footing. What I have on my house now with the cold floor.Stem wall - floating slab usually at garages with step up into house.(except at overhead doors like you said)But we don't have much of a frost depth. I think the code here is 8" minimum cover on top of footing with 20" minimum from grade to bottom of footing. So 12" deep footing and minimum grade gets the 20"In my case, if I can explain this without a drawing, a 12" tall footing, one block, then bottom of slab from there up (or so). I'm going for about 24" from footing bottom to slab top.(12,8,4) This leaves me 8" of dirt between footing top and slab bottom, so I decided to probably dig out the dirt and set the slab on the footing - it would be pretty thick, don't know if that's good or not.So with the insulation idea, i could do rigid insul. vertical from footing top to slab top (and cover the top somehow) and butt into that the under slab insul. What to do with the other 6" between footer and slab?... I'm probably over thinking it. Builders house, you know...going way overboard. How do you do it up north?Anyway, this would seperate the slab from the block wall so cold wouldn't transfer.It doesn't get that cold here, although was upper 20's one night last week. But seriously, when you get acclimated to the heat then anything under 50 degrees is serious cold to us. I was out side working on my crawler a couple weeks ago and was wearing insulated coveralls at about 50 degrees.lolJust wondering if I separated and insulated the slab, could it act as somewhat of a heat sink. Or at least help a little for the money spent.
" more mass always controls sound better than less mass."
Be careful making blanket statements, like this one. This is not true in all cases. A properly designed "sound wall" built with with stick framing construction will be a better sound barrier than a standard concrete block wall, at a fraction of the mass. Everything else, for the most part, I agree with.
I stand corrected. Most STC rated construction OFTEN has a large mass factor. Didn't mean to come across so definative w/ my statement. Foam eggcrate wall finish much like in a sound studio can be virtually dead w/ minimal mass.
Another aspect of sound control is the existence of disconnected physical elements (i.e. elements of the structure that aren't physically connected ... much like having thermal breaks using insulation, physical breaks can control sound).
An example is when I installed a ceiling separating an apartment from my house above, they ran 'hat channel' perpendicular to the joist direction to essentially discconnect my drwall below from being directly attached (i.e. continuously) to the floor joists above.
I've been involved with frame construction that had a wide baseplate, like 2x6 or 2x8 with 2x4 studs every 12" alternating the edge to which they were flush. Weave insluation batts in between. Other than the top plates and the baseplate, GWB from one side has no direct path of sound transmission to the other side. Resilient channels at 90 deg to the studs completes the sound isolation, if necessary.
Sounds like an excellent way to control sound. Similar to standard apartment separation (not sure if they use the 'hat channel', though).
I've got a house here in Tallahasse that is similiar to what you're considering. It's a block first floor with a garage that I used for my shop for a few years. I don't think the cores are filled with concrete, though (maybe a few for structure). Also, my house is pretty shaded most of the day.
Even with the shade, I found it to be pretty hot and humid during the summer months. The only remedy was to run a window AC unit and use some portable fans. I would think that with yours being in full sun it would be even hotter. I have found the key to any kind of unconditioned comfort here is shade and plenty of air movement. You're going to cut out any soundproof aspects of the concrete walls if you open up your windows and doors. It's also a pain to run wires in the conduit and hang anything on the walls.
There seem to be 2 trains of thought down here (hot and humid) on the best way to build for comfort. One is to build lightweight structures that have good cross ventilation and can quickly shed the heat built up during the daytime sun. The other is to build high mass (masonry) structures that are completely shaded from the sun's heat during the day and will store up the somewhat cooler nightime temps. Since you are going to be in the sun, it seems you are stuck using the lightweight (stickbuilt) method. I would suggest using reflective radiant barriers somehow in your walls and low-e glazing.
Hope this helps,
Jamie
Is the lower level going to be buried (ie: a basement)? If so, line the unburied part inside w/1½" xps foam board and you should be good to go. If not, cover the whole outside with 3" polyiso foil-faced and side with something indigestable over metal furring.
Dinosaur
How now, Mighty Sauron, that thou art not brought
low by this? For thine evil pales before that which
foolish men call Justice....
I'd consider a way to redirect the dust collector exhaust outside on nicer days. it could act as a whole house fan pulling in fresh make-up air. quieter too
then when things get too humid or cold cut it off to the the filter and recirculate inside the shop
I'm going with the dust collector with the pleated filter instead of the top bag, since we're talking about a closed up shop. I could probably enclose the top and send the air outside, but that would also send the noise outside. (Neighbors close.....breaking rules.)