Encapsulated/Conditiond Crawlspace

[USAFpj]

So we're on our way with the construction of a new house. The budget didn't allow for a basement, so we're going to go with a taller crawlspace foundation. If doing it, I want to do it right, so being in the humid South, I'm investigating the virtues of an encapsulated, ventless, and conditioned crawl. I've read a lot of great statistics on how this is the way to go in the Southeast, but they all seem to be from the guys selling them!

My contractor has a quote of $4,300 to use "20mil liner, insulate foundation walls, sealant, and HVAC zone for climate control". It seems to me that 70% of homes in the South have a typical crawl, and is there a necessity for this? This should be our forever home, so I want to do it right the first time, but could also put that $$ towards a new shop as well. Priorities should be proper grading and keeping water away via gutters.

Anyone care to give an opinion??

 

[dmccarty]

If you think your inspectors will allow the conditioned crawlspace, I would do it AND THE ATTIC.

Go read what Joe Lstiburek, Joseph Lstiburek, has to say. He is a PHd in Building Science, a couple of engineering degrees and is a PE. I built our house based on the design details in one of his books. He has four books that give design details for different climates in the US, Builder's Guides. I don't know if your area would need the Hot Humid Climate or Mixed Humid Climate book

He has a bunch of information here, Conditioned Crawlspaces about conditioned crawl spaces.

Lstiburek knows what he is talking about.

Later,
Dan

 

[EddieWalker]

I think it's a waste of money. In every house that I've seen it attempted, there are so many holes in the insulation, gaps where its either fallen apart or been taken apart that it's not doing anything.

If I understand this correctly, the theory is to insulate the bottom of the house from the elements to make it easier to maintain inside temperatures and humidity. The question is, how much does this accomplish? The two most important and noticeable areas are keeping the wind out with house wrap, and maximizing your attic space. Nothing else even comes close to creating noticeable results. Then going with good quality windows that are properly sealed. It's shocking how many windows I come across that are not sealed, and even have total air gaps between the outside and interior trim. Air getting through your walls is just like being hosed down by water. It's fast and very hard to fight.

Insulating your walls and good doors add up to the equation, but the results are minimal. You will only get so much out of the walls because heat and cold go up and down. Wind comes through sideways. While the temperature of the ground around the sides of your house will vary a lot, under your house it stays pretty constant if it's dry. If it's wet, you got other issues and adding insulation to a wet area is only going to create a nightmare down the road.

I love reading the articles in the magazines like Fine Homebuilder, where they go out and do everything possible to super insulate the house. Two rows of stud that do not touch each other, mixing foam and fiberglass layers, triple and quadruple pain glass and taping every seal possible. The results are impressive, but when compared to what you get from just doing the basics and spending tens of thousands of dollars less, they don't make any sense. Every time you open the outside door you cause more heat or cooling loss then all that extra stuff is supposed to solve.

It reminds me of a friend who paid $500 for a titanium bicycle seat because it was a few ounces lighter then the one he already had. He felt it was a great deal and that it increased his times when going for a ride. He was also overweight and he has never been in a race in his life. It was all about personal feel good. Same thing growing up working on cars. How much money was spent on headers, carburetor's and manifolds to get a couple more horsepower just to drive around town? I know that in my case, if I had left everything stock, I would have more cash in my pocket with the same results. Most energy savings stuff is just a way to spend a lot of extra money to feel good. The point of going overboard and throwing money away happens when you start trying to get that one extra half a percent improvement.

Eddie

 

[NY_Yankees_Fan]

Eddie, We are buying an 80 year old home with no attic insulation. The attic is completely open and assessable. What is the best insulation for the$? Blown in cellulose, fiberglass or fiberglass up to the top of the joist and a fiberglass over the top of the joist. Any other types, I think foam would be too much. Sorry for stealing the thread......

 

[rrrkkk]

Try this website this guy is very good. I have been to his seminars, he doesn't mind a call and will steer you straight!
Official Website of Doug Rye

 

[DFB]

Is there any local building code specs on crawl space insulation where you are? Just my experience from living in a cold climate if the outside temp should stay below 40F degrees for any length of time you would probably appreciate having the floor insulated if there is no heat under it.

Now around here current building energy codes requires insulation under living spaces. Even with full 8 ft deep foundation the general temperature hoovers only around 50 in the average insulated wall basement usually only ever getting into the 40's in an totally unheated space in the very coldest weather. But they still want you to insulate your first floor joists full depth (be like an R30 value). What gets me with that is most homes have the heat source, usually a hydronic boiler system in the basement so now your blocking any residual heat from warming your floor. :confused3:

I cant answer your question what you should do because obviously I have no experience with how warm or cold your living environment is. I do have warm floors in cold weather around 70 all the time with radiant floor heat. Works for me...my other place had no basement heating system only a first floor wood stove..dang were those uninsulated wood floors ever cold!

 

[vabiker23518]

When I had my cabin built in 2009, I went with the encapsulated crawl space. So far it has worked well with no problems. Dry as a bone. Very satisfied with the results in humid Virginia.

 

[truckdiagnostics]

If i ever built again, no basement and no crawl space, I would still use footings, fill it with sand back fill compact and pour concrete. You could use in floor to heat the concrete, and where you are at not going to take much of a boiler they make instant hot water heater that you can use as boiler also. I agree with Eddie maintaining that vapor barrier over time.... here we put plastic vapor barrier right under the drywall and every time you hang a picture you poke a hole in it, so over time. My opinion crawl space an issue, build with out one.

 

[EddieWalker]

Eddie, We are buying an 80 year old home with no attic insulation. The attic is completely open and assessable. What is the best insulation for the$? Blown in cellulose, fiberglass or fiberglass up to the top of the joist and a fiberglass over the top of the joist. Any other types, I think foam would be too much. Sorry for stealing the thread......

Nothing gives you bigger bang for the buck then blown in insulation. Just be sure that it does not block the soffit vents. R60 is about as good as you can get, and that's achieved with about 24 inches. It's an easy do it yourself if you don't mind sitting in the attic holding the hose for several hours. Feeding the machine is easily done by kids or the wife.

Your goal is to get as high an R value as you can. Spray foam will give it to you with a few inches at a much greater initial cost. Just be careful if you go with foam and not use open cell. That will trap water between the foam and the roof, which will lead to early failure of shingles and decking. Closed cell foam is expensive!!!!

Eddie

 

[tman1020]

Insulated and conditioned crawlspaces are all the rage now. Done properly insulating a crawl is not a bad thing. As far as adding heat to your crawlspace just doesn't make sense to me unless you're looking for a way to waste money and energy.

One thing a lot of people overlook is indoor air quality. It is a huge issue and many times in modern construction houses can get too tight and not allow enough fresh air in. In the event of this outside air mixers are added to HVAC systems.

The reason I bring this up is because if you have a insulated and conditioned crawlspace that is one more area of concern. With a vented crawlspace radon is less of a concern. So in conclusion insulate if you want run supply lines if you want but at least put in the vents in case you change your mind down the road you can always block them off or close them.

 

[dave1949]

If i ever built again, no basement and no crawl space, I would still use footings, fill it with sand back fill compact and pour concrete. You could use in floor to heat the concrete, and where you are at not going to take much of a boiler they make instant hot water heater that you can use as boiler also. I agree with Eddie maintaining that vapor barrier over time.... here we put plastic vapor barrier right under the drywall and every time you hang a picture you poke a hole in it, so over time. My opinion crawl space an issue, build with out one.

I would choose this over a crawlspace too. The footings give a solid, stable foundation for the structure and are a wash cost-wise compared to crawlspace walls, perhaps less even.

The only potential drawback to consider is the drain and waste lines will be under the concrete slab unless you do some fancy design work clustering the plumbing and incorporate an underground pipe chase to the outside wall. Otherwise, if repairs are needed, it will be a major project compared to a crawlspace. Mine are under the slab and I hope to never need to repair anything. I think that is a fairly rare problem.

 

[DFB]

I would choose this over a crawlspace too. The footings give a solid, stable foundation for the structure and are a wash cost-wise compared to crawlspace walls, perhaps less even.

The only potential drawback to consider is the drain and waste lines will be under the concrete slab unless you do some fancy design work clustering the plumbing and incorporate an underground pipe chase to the outside wall. Otherwise, if repairs are needed, it will be a major project compared to a crawlspace. Mine are under the slab and I hope to never need to repair anything. I think that is a fairly rare problem.

The new building where I work was built like that (sans any radiant heat) frost walls and insulated slab...before construction was even completed we had to cut the new floor move drain lines and patch it...hey plans change :laughing:

 

[dmccarty]

Our house has a finished, colored concrete floor, aka a slab. Slab homes are very common in Florida and all of my family members, except one, lived in a slab home for decades. Never a problem with the plumbing that required tearing up the slab. The one family member had to have a bit of a crawl space because the house was built on a slope. When they sold that house, they bought a slab house.

Our house is on a slope but we put in a slab even though that required the foundation to be filled up with tons of 67 stone. The down slope side of the house is about 5 feet above grade so we needed a fair amount of gravel. We did not want the problem that occur with crawl spaces and wooden floors. We also wanted the mass of the slab to moderate the temperature in the house which has worked real well. We thought about putting in radiant floor heat but for our climate it was not worth the extra cost.

It was funny watching the Directv installed walk around the house looking for a crawl space to access so he could put in the coax. :laughing::laughing::laughing:

Later,
Dan

 

[DFB]

Let me ask you some of you guys what type of drain pipe material do some of these slab built residential homes have..cast iron, ABS, PVC?

Our new building at work was built to meet commercial inspection code so it's all cast iron below grade.

 

[dmccarty]

Let me ask you some of you guys what type of drain pipe material do some of these slab built residential homes have..cast iron, ABS, PVC?

Our new building at work was built to meet commercial inspection code so it's all cast iron below grade.

PVC is what we have in our home. I wonder if some of the older homes, my granny's house was likely built in the 50's, so I would guess they used cast iron?

Later,
Dan

 

[s219]

When we built our new home in 2012-2013, we went with a sealed/conditioned crawl space. It's pretty much the standard in this area now, and my understanding is that it has become a "best practice" in the humid southeast US. So far I am very impressed with it. The crawl is dry and clean, and there are none of the issues you'd have with a vented crawl in this part of the country.

One corner of our home has a 7' tall foundation height, enough for a full size door. We poured a slab down in that corner, and that's where the hot water heater, well tank, and water treatment tank are located. It's also a great storage space, so I have some shelving down there. Because the area is conditioned, we store furniture and other household items down there, which has been awesome. Could never do that in a vented crawl. From that tall corner, the foundation tapers to about 2' height at the other extreme. In between the two corners, I have all sorts of stuff stashed, including spare lumber, a kayak, etc. I'd say it's like having 60% of a basement, and really helps me keep other areas of the home neat, but still have my "junk" nearby stored in a clean dry place. Almost like an onsite conditioned warehouse.

The HVAC ducts for the first floor of the home are down in the crawl, and there is one small extra register on the end of a trunk that pumps conditioned air into the crawl space. There was a return duct installed (code requirement), but it is blocked off at the recommendation of our HVAC guy. The idea being to keep a slight positive pressure in the crawl space, and let the return air bleed through all the cracks/gaps/etc between the crawl and first floor only when the blower is running, rather than have a return duct that is always open to the first floor. I imagine the same result could be achieved with some sort of passive damper on a return duct.

Our previous house was built in 2000, and had a regular vented crawl. I can't say I ever had problems with it other than a little mold at one point. But I was careful to check down there periodically and make sure the vapor barrier was in good shape (that was only plastic) and the vents were open in summer. The thing is, other people in the same neighborhood had real problems with their vented crawls, such as dampness, mold, and odors. Some had to install fans and additional venting. I am only guessing, but it's likely those other homes had moisture sources, either due to poor drainage, poor grading around the home, or just bad location.

Even conditioning the crawl in our new home, our heating/cooling costs are about 2/3 of the old home, per square foot (living space only). The new home happens to be 1.5 times bigger in living space, not counting the crawl. If I had to take a stab at factoring in home size as well as crawl space volume, I'd say there is little to no cost to conditioning the crawl, all said and done. Some of that is due to having a more efficient geothermal HVAC system in the new home of course, so exact estimates aren't possible. But suffice it to say that even when conditioning the crawl, we are spending less on HVAC per square foot of living space than the old house.

 

[Country Geek]

Yes to conditioned crawl space. 25 years of research at NCSU has resulted in the best practice for humid southeastern areas being changed to insulated/encapsulated. Others on this thread have quoted other experts. Here is another site of experts who aren't sellers: http://crawlspaces.org/

I had mine done this past fall and it's like a new house. Someone else mentioned concerns about indoor air quality. An encapsulated crawlspace vastly improves indoor air quality. The 20mil barrier blocks radon from coming up into the crawlspace. But the biggest indoor air quality problem in houses in the southeast (after carpet and other VOC outgassing that you see everywhere) is mold and mildew getting into the HVAC system from the crawlspace. The previous standard, vented crawlspace, draws in warm humid air which condenses on all the HVAC ducts and any other equipment down there and over time you end up with a moldy mess that circulates throughout your house. I had my 15 year old HVAC system replaced at the same time I did my encapsulation and it almost made me sick seeing that equipment and ductwork that was removed. Black with mold and mildew from being in a vented crawlspace, not to mention significant rust on the condenser.

Also rural dwellers have to think about critters. Raccoons had figured out how to pull out the foundation vents and get into my crawlspace with very unpleasant results. In an encapsulated crawlspace, the foundation vents are covered and blocked off (from the inside, from the outside the grills are left in place and it looks like no change).

Like anything you do have to stay on top of maintenance. Repair any rips that occur in the 20 mil barrier and any other damage that occurs. EddieWalker posted that damage to the envelope defeats the purpose. He's right, but so does damage to the envelope of the living space. If one can be kept sealed with normal maintenance, so can the other.

 

[DKCDKC]

I built my ranch home in 2000 over conditioned crawlspace - and remain glad I did. Floors are warm, no worry about freezing pipes during cold snaps, makes wonderful storage, etc. I had the sealed heavy plastic laid on the ground and put padded pallets on it for storage. Radon tests have been largely negative, but I took the precaution when I built the house of laying some small connected PVC pipes just under the plastic with lots of holes in them. They connect to a small pipe that goes straight up to and above the roof. Not only does it vent moisture, it also vents any radon that might appear.

 

[dave1949]

Let me ask you some of you guys what type of drain pipe material do some of these slab built residential homes have..cast iron, ABS, PVC?

Our new building at work was built to meet commercial inspection code so it's all cast iron below grade.

PVC is what I have.

 

[EddieWalker]

Let me ask you some of you guys what type of drain pipe material do some of these slab built residential homes have..cast iron, ABS, PVC?

Our new building at work was built to meet commercial inspection code so it's all cast iron below grade.

Schedule 40 PVC. Being smooth, it allows solids to flow a lot better then cast iron. When properly primed and glued together, it will never fail.

Eddie