Insulate basement + crawl space walls to save energy?

[brainless]

Live in 60 year old 1300 Sq Ft single story brick house with full basement, it has recent 600 Sq Ft addition with about 3' crawl space. Live in Michigan (zone 5) and winter heating bills are a killer. My basement is very cold and drafty in winter...in dead of winter temp check showed around 37 degrees...I have hot water heating too by the way. The House came with newer Anderson windows and two years ago I blew cellulose insulation into all walls that were not insulated...also added about 6" in attic....so total of about 12" of cellulose there. Oh and I also did my best to caulk everywhere possible in basemen last winter, but seemed not to help much.......I have noticed that the inside walls of basement are like ice cold to the touch too. would it be worth while to dig down a couple of feet and insulate the outside of basement and crawl space?? If so how to do it? Any advise appreciated...

[aemeijers]

Worth it as in a more comfortable house, yes. If you can tie the foundation wall temp to ambient below-frostline depth temp, the basement and house will be a lot more comfortable. It almost becomes a bermed home if you do it well enough. Worth it on payback period, is a whole 'nother question. Unless you have the strength, willpower, and time for DIY, it is a lot of manual labor to insulate below frostline on the outside. And I do mean manual labor- it is almost all hand work, unless you want to destroy the yard and all plantings. Hand labor=expen$ive. Most people give up some R-value to save front money, and insulate on the inside. Often overlooked spot- is the band joist insulated, above the sill plate but below the first floor decking? Also common to get air leaks right at the sill plate, if they didn't gasket it correctly before they laid it out.

Standard caveats apply about not creating leak paths by skinning the wall, and having a vapor barrier on the cold side of the wall. Unless your upper walls already happen to stick out unusually far, you will need a big Z-flashing at the top of the insulation, and it will look funny. May be able to disguise it with a wide trim board something. They sell faux-stucco finish hi-density foam panels for the very application you are thinking about. They go up with construction adhesive, and you can even get color-matched putty and a texturing roller to hide the joints.

-- aem sends...

[cshenk]

(zone 5) and winter heating bills are a killer. My basement is very cold

Drafty? I live in a southern clime now so am not experienced here, but drafts usually mean there's doors or windows that arent sealed right. Can you explain the setup a bit better?

[hallerb]

ulation into all

use closed cell expanding foAM, MOISTURE DOESNT EFFET IT.

[hallerb]

Get a blower door test, they pressurize the building to look for leaks

[jmeehan]

Yes insulating the basement will help. You can do it several ways. Which is best will depend on the current construction. Assuming it is concrete block, which is common in your area AND assuming it is dry (which is less common) I would use foam insulation made for that use or frame it out and use fiberglass. I believe there is even a fiberglass product made for that use today.

What is important is to make sure the wall is DRY.

Next put most of your effort on the top half of the wall. The bottom half is already insulated be several feet of dirt. Dirt is not a great insulator by with three or four feet of it, it does add insulation.

Good Luck

[ransley]

To pinpoint air leaks and know what you need get an energy audit and blower door test, also an IR photo. A blower door test will give you a computer printout of air exchanges per hour and how many there should be, the tech, with a smoke stick will show you what is leaking. 12+ cellulose in attic is not optimal in zone 5, first its likely 9"" now, cellulose settles, but 12" is maybe R 43, optimal is near R60.

has good info

[trader4]

tar.gov=A0has good info

That's where I would start too. For a basement to be drafty means there has to be large air leakage somewhere. That is probably the biggest problem, and until that is fixed adding insulation won't make much difference, unless it happens to fix the leakage too. But better to start with finding out how air is getting in.

[aemeijers]

R60.www.energystar.gov has good info

We've discussed all this to death on here before. Around here, there is no way to get an energy audit/thermal camera pictures/blower door test etc. None of the local utilities offer the service, and the local HVAC companies just want to sell new systems. I have looked, several times, and I can't find a company within 100 miles to come do the site survey. So, I have been doing seat-of-the-pants improvements based on personal experience and discussions on here, and next on my list is to buy one of those IR thermometer things, and start logging some data under various sunlight and weather conditions, and hope a pattern pops out.

-- aem sends...

[PerryOne]

You do not mention how much insulation you have in your floor? Remember heat always moves to cold, that means down as well. What you need is to disconnect your inner living space from the main structure of the building. That means lining the inside of the whole of the exterior walls, the top ceiling and floors with two inches of polystyrene or similar to stop the cold bridging of your existing insulation. There are probably lots of places where the inner walls are in direct contact with the outer shell. It is these points where the heat leaks out. Perry

[brainless]

No insulation in floor of this house...2 inches of polystyrene on inside of outside walls? I am sure that would be very effective, but how do you do that? drywall over it? and what about windows and doors? sounds very difficult to do....the floor is surely doable, but would it then be colder in basement? and would I need moisture barrier.....will probably try insulating outside to frost line (if I can work out how to do)...but will have to wait till next summer.

[Michael B]

Minimal return on the labor, might be better insulating the walls inside. If it's practical, might consider replacing basement windows with a single row of glass block at the upper level, attach plastic to the house and take it out about 15 feet, then cover with soil to the bottom of the glass blocks. Frequently, walls are colder because there's not good positive slope away from the structure. Dry soil is far more insulative than wet soil. And clay dirt can be your friend.

[Michael B]

Have you installed a setback thermostat yet? Extremely good payback on that. And look for cobwebs in the basement. Those spiders find the air leaks nicely and identify them well..

[PerryOne]

======================== Its surprising how often homes are built without floor insulation, as you have a basement then four or five inches of polystyrene pushed up tight against the floor will do the trick, make sure its a tight fit, holes equal loss of heat - heat always moves to cold and it will move through the smallest hole. In a strong wind a hole 3 eights of an inch can strip the heat from a home. Yes, it will make the basement colder, but do you have anything down there that will freeze? If its only pipes, then decent insulation, sealed cell at least one inch thick will do, if it really freezes then electrical resistance wire wound round the pipes and controlled by a thermostat set at 35f will do the trick at the cheapest to run cost. As far as the walls go, stick the polystyrene to the existing walls, then stick drywall over. Polystyrene is almost water proof to 0.01%. On my first ever job I used nails through the drywall and polystyrene, then every time it got cold the heads of the nails showed up. Insulating to the frost line, or laying polystyrene on the ground all round the home and covering it with concrete does work but, it is expensive and a lot of hard work. Better to think of your home as a tight comfort zone and keep the heat in the space you live in. Windows need to be double or treble glazed, but this needs to be made in a factory and it is expensive. You have to look at the long term, are you likely to live there for thirty years?