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Old 09-11-16, 03:25 PM   #1
MEMPHIS91
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Default MEMPHIS builds a house

So I never thought I would say this but we now have plans on moving, the current location/house/stress is not what we want. So we have plans on moving to another county (this one is getting way to strict in all the wrong ways). Looking at a 1,500-1,800 square foot 3 bed 2 bath house with a 10x12 (not heated and cooled, just insulated) basement/root cellar. I want it to be as efficient as money will allow, I will doing most of the work myself as NO one in the area knows how to build a tight super insulated house.

Thoughts so are:
-2x6 exterior walls on 24" centers with 1 of spray foam and the rest filled with fiberglass or cellulose

-3/4 ridge foam wrapped, with 1/2 osb sheeting on top and then wrapped in a good moisture barrier/air seal

-roof with 3/4 ridge foam and vertical 1x4's strips to allow the silver tin roof to vent.

-vented brick exterior

-dense packed cellulose in the ceiling to about R40

-insulated slab floors (though I am finding places saying uninsulated is better)

-vinyl 9mm fake wood tung and groove flooring

-5 total mini splits 2 of these for where we will be most of the time Gree Crown 9 000 BTU Ductless Mini Split System Remote 25' Lineset 208 230V | eBay and a set of these for everywhere else 27000 BTU Tri Zone Ductless Mini Split Air Conditioner and Heat Pump SEER 23 | eBay

-Looking at this hrv Panasonic FV-04VE1 WhisperComfort Ventilator, ERV

-There will be a wood fireplace for back up heat

-all led lighting wired 12v

-all dc ceiling fans (each bed room and one in the great room)

-heat pump water heater in the basement/root cellar

-good at least triple pane windows with double low e coatings

My goal is to make a house that isn't out of the park expensive but can still out perform 90% of houses built today.

I think I am set on no geothermal for the main house, I might put in tubes in the floor just in case I want to build a DIY geothermal heated floor for the main rooms of the house.

I am doing tons of research into how to position the house for best solar

My cooling days are more than my heating so im looking into how and where to add radiant barriers.

Opinion on if a should build in a way to prevent thermal bridging? Or is it not as big a deal down south?

Any tips, tricks, or links would be awesome. This is going to turn into a long long thread as I post building pictures and as always a step by step over view.

Thanks guys and Shalom

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Old 09-11-16, 03:49 PM   #2
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I would highly recommend you go with non-wood SIPs (Structurally Insulated Panels). May cost more for the materials but time, ease, and insulation value is not beatable.
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Old 09-11-16, 04:09 PM   #3
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natethebrown, I am looking into them now, why non wood?
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Old 09-11-16, 06:48 PM   #4
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Quote:
Originally Posted by MEMPHIS91 View Post
natethebrown, I am looking into them now, why non wood?
So you don't have to fool with insects or molds, and they are probably lighter with better insulation value. The negative is you have to now use screws to attach to the steel.

Here are some old pictures of my dad's addition (his addition is about 95% complete now):







You can see each SIP is about 4'x10'x~1' thick and is light enough for two people to handle. Any ways, if you decide on wood SIPs, no problem, I just believe the "standard" stick frame home is out of date and so low tech compared to what building technology we have now.
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Old 09-12-16, 03:00 AM   #5
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The Double stud wall is the cheapest to build but I don't think it is the best wall. if you are ok with foam, you may be able to find used foam insulation for cheap enough that a double stud wall may not make sense, especially if you are the labor supply. There is also adding foam strips to the interior of the studs with a 1x on the interior side for a nailing strip. This can add a bit more cavity depth and also reduce thermal bridging.

As far as sub slab insulation is concerned my inclination is to say either that or perimeter insulation is a good idea. however I would hire Energy Vanguard or some other firm (Allison Bailes at energy vanguard can probably recommend someone if they can't do it) to do some energy modeling and cost optimization. Now is the time to start that conversation as they can help you avoid design issues that can cause large energy penalties.

As for GTHP, I'm meh on them. great concept, not so great execution. The other issue I see judging at least by the ingrams site is that they really don't have something small enough for your situation. I'm betting if you build your house well you will see an AC load of around 1 ton. Heck even finding conventional equipment that small can be a challenge. The majority of your heating and cooling hours will be at part load conditions, this is the area that mini-splits excel at, and where they beat GTHPs.

Quote:
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I would highly recommend you go with non-wood SIPs (Structurally Insulated Panels). May cost more for the materials but time, ease, and insulation value is not beatable.
Not for a first time DIYer. If he can find a contractor with experience with them then they can be a viable option. The SIPs supplier may be able to recommend someone.
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Old 09-12-16, 06:52 AM   #6
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Steven those numbers are for sure nice, I'm still concerned with it being over sized, but at that price your right it is hard to beat. We are not stuck on the mono pitch yet. I think as long as we have vaulted ceiling in the great room/kitchen area we would be happy. I still hate the idea of having my duct work in the attic unless of course I can have the rather a insulated, but then I hate the idea of heating and cooling my attic. So many options, so much more research. I wish more people had these type systems/houses in my area.

DEnd, I am really liking the idea for sips they seem quick and a good product, I'm going to do some calling around to see if anyone in the area builds with them. I have a lot of connections around here. I can make more money at my job than I can save doing the time consuming labour parts of the house. I'm the general contractor for sure though.

Thanks for all the input guys.
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Old 09-12-16, 02:03 PM   #7
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Quote:
Originally Posted by MEMPHIS91 View Post
Steven those numbers are for sure nice, I'm still concerned with it being over sized, but at that price your right it is hard to beat. We are not stuck on the mono pitch yet. I think as long as we have vaulted ceiling in the great room/kitchen area we would be happy. I still hate the idea of having my duct work in the attic unless of course I can have the rather a insulated, but then I hate the idea of heating and cooling my attic. So many options, so much more research. I wish more people had these type systems/houses in my area.

DEnd, I am really liking the idea for sips they seem quick and a good product, I'm going to do some calling around to see if anyone in the area builds with them. I have a lot of connections around here. I can make more money at my job than I can save doing the time consuming labour parts of the house. I'm the general contractor for sure though.

Thanks for all the input guys.
Why do you hate the duct work in the attic? If it is insulated you are conditioning the space regardless, and you get conditioned storage space. If it is un-insulated then a well sealed duct system buried in the insulation is a fairly decent system, though you would not want to put any mechanical equipment in there. I agree that it is not the best solution (due to low fault tolerance), but it can be a workable one.

I don't really have anything against SIPs, but their details are not common knowledge. Yes they are fairly simple, but finding people who know how to move the Sips efficiently and safely as well as detail any penetrations they have, and know the tricks of wiring etc... is a lot harder than finding people who are familiar with the details of stick construction.

I would say you need some form of slab insulation regardless. At minimum you need to address the thermal bridge at the outside of the slab. BSC has a few ways to do this: https://buildingscience.com/document...059-slab-happy
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Old 09-12-16, 04:02 PM   #8
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Why do you hate the duct work in the attic? If it is insulated you are conditioning the space regardless, and you get conditioned storage space. If it is un-insulated then a well sealed duct system buried in the insulation is a fairly decent system, though you would not want to put any mechanical equipment in there. I agree that it is not the best solution (due to low fault tolerance), but it can be a workable one. I have duct in the attic now. It is a pain to check on and work around in the attic, plus mine wasn't done right so I am biased.

I don't really have anything against SIPs, but their details are not common knowledge. Yes they are fairly simple, but finding people who know how to move the Sips efficiently and safely as well as detail any penetrations they have, and know the tricks of wiring etc... is a lot harder than finding people who are familiar with the details of stick construction. I did some calling around today there are only a few homes that were built with sips in the Oxford area. And those don't look like they were done right. I will either hire a crew or just do them myself.

I would say you need some form of slab insulation regardless. At minimum you need to address the thermal bridge at the outside of the slab. BSC has a few ways to do this: https://buildingscience.com/document...059-slab-happy
Yes thermal bridging at the outside edge is on the list, I got about 4 sites all saying the same info, which is a good thing
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Old 09-11-16, 04:49 PM   #9
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Don't obsess on PV solar roof orientation. So long as a roof area is within 20 degrees of true south each direction, this still gives you 90-95% of true south solar power.

Mistake on triple pane. In your southern climate, you don't need it in the winter - money spent here is a FAR too long payback. Double pane is certainly enough - but buy good ones, not the locally built vinyl clad cheepos. But you DO need to pay attention to summer overhangs on east, west and southern windows to prevent solar gain (maybe this is where you meant orientation).

In your area, do NOT insulate slab as you need to bleed off heat in summer. Your ground temps are just not that cold in Mississippi.

Outside air moisture and interior humidity are your enemy. Put your dryer in a room with outside air inlet and seal it off with good closing (sealed) door. A dryer pushes some 500-600 CFM per minute out of the house and conditioned air pushed out means that air (humid/moist and hot) MUST come in as house is now a vacuum.

Two ERVs are a necessity with a tight home of this size. The ones you are looking at are great in bathrooms to vent moisture 24x7 and total also provide about 40 CFM total (low speed). When bathroom/shower is in use (DPDT switch to bathroom light), then HRV goes into high fan speed mode (total 80 cfm).

I would still do geothermal for ducted AC . . . . an open loop system. You need to put in a well anyway. That many minisplits gets you into expensive territory. I have recently bought from Ingrams and they have a very nice three ton GTHP for about $3100. Forget the thermal heated floors - you just do not get that cold to justify that cost.

I would do SIPS for roof as you get everything for not a lot of $ and will be installed in one day (roof decking, insulation, interior trusses, R40 foam and inside OSB). SIPS with 8 inch foam (R40) are easily available. You can get 12 inch, but your local conditions don't merit. You can span up to 40 feet with SIPS. Makes interior layout easy with no load bearing walls needed.

Infiltration is your enemy - not heat or cold. Build yourself a temporary blower door (or window) with an old HVAC squirrel cage blower and simple water manometer. I use dry ice for "smoke" to detect leaks.

If you are in a rural area, build a pond (discharge water from open loop geo unit into this) as this markedly lowers your home insurance. Home insurance goes WAY up in rural areas with volunteer fire departments. You will also get a discount for metal roof (good idea). A fire pumper can dip suction hose into pond. Pond got me a 30% discount on my home insurance . . .

Do you really mean "as efficient as money will allow"?

Why a fireplace? This is a true energy waster. Put in a good wood burning stove that has opening (and closing doors). You can see fire if you want to, but can close it up for more efficient use. - but make it small (24 - 36 KBTU/hr) as it will otherwise overheat the house.

Mazel tov!


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Old 09-11-16, 07:31 PM   #10
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Don't obsess on PV solar roof orientation. So long as a roof area is within 20 degrees of true south each direction, this still gives you 90-95% of true south solar power. I forgot to mention that we are going with a single pitch/mono pitch roof so I will have tons of room for solar.

Mistake on triple pane. In your southern climate, you don't need it in the winter - money spent here is a FAR too long payback. Double pane is certainly enough - but buy good ones, not the locally built vinyl clad cheepos. But you DO need to pay attention to summer overhangs on east, west and southern windows to prevent solar gain (maybe this is where you meant orientation). Awesome to know on the windows thank you, and yes that is what I meant.

In your area, do NOT insulate slab as you need to bleed off heat in summer. Your ground temps are just not that cold in Mississippi. 10/4, that saves more money.

Outside air moisture and interior humidity are your enemy. Put your dryer in a room with outside air inlet and seal it off with good closing (sealed) door. A dryer pushes some 500-600 CFM per minute out of the house and conditioned air pushed out means that air (humid/moist and hot) MUST come in as house is now a vacuum. 10/4, I was thinking about something like that as well

Two ERVs are a necessity with a tight home of this size. The ones you are looking at are great in bathrooms to vent moisture 24x7 and total also provide about 40 CFM total (low speed). When bathroom/shower is in use (DPDT switch to bathroom light), then HRV goes into high fan speed mode (total 80 cfm). I'll plan on 2 Erv's

I would still do geothermal for ducted AC . . . . an open loop system. You need to put in a well anyway. That many minisplits gets you into expensive territory. I have recently bought from Ingrams and they have a very nice three ton GTHP for about $3100. Forget the thermal heated floors - you just do not get that cold to justify that cost. I have no attic space with a monopitch roof, and being on a slab I can't go through the floor for a ducted system, these mini splits are pretty amazing and I think we save money on Install vs the geothermal. The only well I plan to have is a solar powered well pumping into a small water tower with a booster pump if needed.

I would do SIPS for roof as you get everything for not a lot of $ and will be installed in one day (roof decking, insulation, interior trusses, R40 foam and inside OSB). SIPS with 8 inch foam (R40) are easily available. You can get 12 inch, but your local conditions don't merit. You can span up to 40 feet with SIPS. Makes interior layout easy with no load bearing walls needed. The sips I am looking at are claiming R7 per inch, so I'm thinking of using their 4.5" on the walls and 8" on the ceiling/roof. Polyurethane Structural Insulated Panels | Energy Efficient Eco Panels SIPs - About Eco-Panels

Infiltration is your enemy - not heat or cold. Build yourself a temporary blower door (or window) with an old HVAC squirrel cage blower and simple water manometer. I use dry ice for "smoke" to detect leaks. I got a huge 4,000 cfm greenhouse fan

If you are in a rural area, build a pond (discharge water from open loop geo unit into this) as this markedly lowers your home insurance. Home insurance goes WAY up in rural areas with volunteer fire departments. You will also get a discount for metal roof (good idea). A fire pumper can dip suction hose into pond. Pond got me a 30% discount on my home insurance . . . I'm a fireman, I am looking into a small pond, but I think if my water tower can hold 1,500 gallons I can get away with that as well.

Do you really mean "as efficient as money will allow"? Yes

Why a fireplace? This is a true energy waster. Put in a good wood burning stove that has opening (and closing doors). You can see fire if you want to, but can close it up for more efficient use. - but make it small (24 - 36 KBTU/hr) as it will otherwise overheat the house. I should I have been more clear, wood burning insert is the plan, we like the look of the brick and the fire.

Mazel tov! Thanks


Steve
Thanks so much for your help, I have written down your ideas and they will go into planning
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