DIY Home Improvement, Remodeling & Repair Forum > DIY Home Improvement > Insulation and Radiant Barriers > Insulation help in attic/half story





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Old 11-14-2010, 03:58 AM  
Perry525
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That should work.

The remaining weak link will be the new windows.
I solved the problem by having quadruple glazing.

That is, two sets of double glazed windows, with a gap of eight inches between the inner and outer panes of glass, with venetian blinds in between.
This enabled the blinds to block the direct sunlight while reflecting the light into the room.

In the normal way double glazing with a venetian blind, results in the blind becoming very hot and transferring the heat into the room, the second set of double glazing keeps the heat inside the window recess.

If I ever get round to building a home from scratch, I will copy the Europeans, in France, Germany and Switzerland.
They recognize that the best asset is shade, they nearly all have external roller shutter blinds, these are kept in a box either above or below the window and are wound into place eith by hand or using an electric motor, it is a system that keeps the heat outside, leaving the double glazed windows cooler in the shade.
They can of course be stopped in any position to allow light into the room.



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Old 11-15-2010, 07:32 PM  
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Have you thought about spray in foam? Have you had a cold drink in a foam cup in the summer and noticed, no sweat? same thing in your walls. I have been getting the spray foam installed instead of fiberglass for a few years now. It will pay for itself, in heating and cooling bills. The last job I did, I was charged $1.55 per sq ft for walls.



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Old 11-23-2010, 10:38 AM  
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Spray foam is what I'll be using. I got an estimate last Friday. The cost to do the entire underside of my roof at 5", as well as 2 gable walls and the 10x8 wall that I'll have when I complete the dormer, is $1500. He's going to use open cell on that. I was surprised at how inexpensive it was. The same company is going to lay plastic in my crawlspace and spray foam the inside of the foundation with closed cell foam for $600. I'll have some before and after pictures of the spray foam job, so maybe I'll post them here.
Here's where the roof is going to be cut out and raised, and you can see the pathetic insulation job that the previous renovators did; that's R13.


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Old 11-24-2010, 11:44 AM  
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A lot of people seem to believe that laying plastic sheet over the ground in the crawl space will stop the moisture in the ground from rising and condensing on their joists and thereby prevent mold and wood rot.

This seems to be based on the observation that when you lay plastic sheet on the ground and then lift the plastic sheet there is always condensation on the underneath of the plastic.

The facts are that the temperature in the crawl space is always so low that the air is to all intents dry and the ground is even cooler, the moisture in the ground does not suddenly decide to warm up and project itself upwards onto your woodwork.

Water vapor always moves from warm to cold, therefore it stays where it is. Unless you have large gaps under your home, where freezing air can be sucked under the home by the passing wind. Then moisture will migrate into the freezing air.

The wood of your floor will always be warmer as a certain amount of the heat in your room escapes downwards by conduction and radiation.

This brings me to the spray foam on the inside of the foundation. What is this supposed to do?

As I have written many times, heat always moves to cold.

When insulating your home, you need to keep the heat inside your comfort zone during the winter and to keep the heat out in the summer.

To make this process as economical as possible, the insulation needs to be as close to the comfort zone as possible.

Therefore, placing insulation on the perimeter of the crawl space will do nothing for you in summer or winter.

Placing the insulation on the room side of the downstairs floor will keep the maximum amount of heat both in during the winter and out during the summer.

However, because of the problems caused by raising the floor level, raising door frames etc. most people settle for having the insulation tightly packed between the joists under the floor. As with your roof, the joists then become the weak link and it is usual to fix two or three inches of polystyrene sheet across the floor to keep the heat inside the joists.

There is no point in allowing even a small amount of your expensive heat to escape through the floor into the proportionally vast crawl space, where it will in all probability not even raise the air temperature by one degree.

May I suggest that you use that infrared temperature gauge to read the floor temperature inside the rooms, then read the under floor temperatures and the bottoms of the joists, then the ground and foundations. Get a real idea of what is involved.

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Old 11-24-2010, 12:27 PM  
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I understand your points, and ideally, I would insulate the room side of the floor, while laying a new subfloor over the original heart pine, and then a new wood floor. I have plenty of ceiling height and removing baseboard and door jambs doesn't bother me. The problem is the cost of a new floor. Incidentally, because my heart pine floor is not level, and jacking it up in the necessary places isn't feasible, I do plan on eventually leveling it on the top side and doing exactly what we're discussing. That may be some time from now, however.

Right now, my crawlspace is actually a little bit drafty. I'm hoping to have someone do repair work on the brick foundation, followed by a concrete stucco. Doing that and sprayfoaming the inside perimeter would at least keep the crawlspace as water and air tight as it practically can be kept. My HVAC ducts all run in the crawlspace, and my water heater is down there too. The sprayfoam should at least help in that regard.

You mentioned that the heat upstairs keeps the joists warm enough to prevent them from being moist. My understanding is that for this reason, it is not necessarily a good idea to insulate between the joists. The insulation between the joists will then stop the heat from reaching the bottom of the joists. The only way to prevent this problem is to sprayfoam to the bottom of the joists, completely covering the wood. That would be cost prohibitive, as well as physically impossible in my circumstances. There is so little clearance in my crawlspace that I was surprised when the insulation company said they had people who could get in there.

Thanks for your continued input. I've learned a lot in this thread.

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Old 11-25-2010, 11:58 AM  
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Think of using a steel poker in the fire, leave it in the fire long enough and the heat travels along the bar by conduction and the end burns your hand, to avoid this, perhaps you wrap the end in a rag, insulating your hand from the heat and you can hold it a bit longer. before you get burnt.

The steel bar heats at one end, the heat travels along the bar, and as it does heat is radiated and convected to the sides, with the bar gradually dissipating its heat until it reaches the point where all the heat is lost into the air, and the far end remains cold in your hand. (for a time)
The heat input, being balanced by the heat loss over distance.

Your joists work exactly the same.

The heat is input from the air above the floor.

The heat travels by conduction down the body of the joist, loosing its energy by radiation and convection to the sides as it goes adding a small amount of heat to your crawl space.

Filling the spaces between the joists with insulation, helps slow down the loss by convection enabling the heat to travel further by conduction, leaving the end/bottom of the joist hotter, sooner and longer.

Wood used to be considered a good insulator, then modern insulators like, polyurethane, polystyrene, aerogel etc came along, things that slow the loss of heat to a far greater extent.
And wood became a heat conductor and the weak link in keeping your home warm.

There is little heat loss through the floor, compared with your windows, ceilings and walls.

However, because our feet are in direct contact with the floor, our body heat quickly disappears downwards into the floor and out into the cold sky and we can end up with cold feet.

Something, we do not feel so intimately, with our body's insulated rather more by warm air when indoors, but stand with your back against an uninsulated cold wall and you soon notice the heat loss.

Its interesting, that many people loose a 2 or 3 foot wide strip along their outside walls during the winter, with the heat loss through the air into the walls making that part of the room unusable.

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Old 11-25-2010, 03:28 PM  
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“Kindly note that foam shrinks over the first 5 to 10 years by 15%.” ---- Perry, I’ve researched that statement and only found SPF will shrink only when improperly mixed (two parts).

You may find this interesting: BSI-009: New Light In Crawlspaces — Building Science Information

Why open cell foam/
• “In climate zones 5 through 8, the “air impermeable insulation” must be a vapor retarder (Class II; 1.0 perm dry cup or less), or have a vapor retarder coating or covering in direct contact with the underside of the insulation. For instance, an air impermeable but vapor permeable spray foam (0.5 pounds/cubic foot) would not meet this requirement, unless a vapor retarder coating were applied (R806.4.4).” IRC FAQ: Conditioned Attics — Building Science Information
“On the other hand, open-cell spray foam (average density, 1/2 pound per cubic foot) is not a vapor retarder. Installed at a thickness of 3 inches, open-cell spray foam has a permeance of about 16 perms, making it fairly permeable to water vapor.” A Close Look at Common Energy Claims - EcoHome Magazine A Close Look at Common Energy Claims - EcoHome Magazine
Air seal the knee walls from the sloped ceiling to prevent air movement behind the drywall. Use the ADA: Info-401: Air Barriers
Air seal the attic and install foam board or house wrap on the attic side of knee wall, under and over it: How to Seal Attic Air Leaks | The Family Handyman
http://www.simplesavings.coop/simplesavings/SIMPLESAVINGS%20knee%20walls.pdf
Gary

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Old 11-26-2010, 03:43 AM  
Perry525
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[QUOTE=GBR;51528]“Kindly note that foam shrinks over the first 5 to 10 years by 15%.” ---- Perry, I’ve researched that statement and only found SPF will shrink only when improperly mixed (two parts).

You may find this interesting: BSI-009: New Light In Crawlspaces — Building Science Information

As you probably know Dow brought their styrofoam to market 51 years ago.
Since when foam in its various forms it has been studied most carefully.
Evidence shows that foam does indeed shrink by 15%.
May I suggest that you look outside the USA.

By the way, thanks for the lead, I am fully aware of the article.

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Old 11-26-2010, 08:05 PM  
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I've only entered "SPF shrinkage" on the internet search, where- outside the U.S.?
Do you remember any more about the article statement? Who, where, why...... ?

Thanks, Gary

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Old 11-27-2010, 04:40 AM  
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Quote:
Originally Posted by GBR View Post
I've only entered "SPF shrinkage" on the Internet search, where- outside the U.S.?
Do you remember any more about the article statement? Who, where, why...... ?

Thanks, Gary
Hi, I was researching the European Common Market, following up on their building research pertaining to Passive House building.

I drop in on this from time to time to see progress.

They have been studying building insulation since the early 1980's. After Denmark managed to produce some very tight houses that were well insulated but subject to shocking levels of condensation and mold.

This was then taken up and followed through in Germany and is now going to be standard all over the EU from 2016.

They are working on the basis, that every possible type and style of home can be built to Passive House standard, which in the EU is about a hundred times more demanding than our standards.

I cannot find the article but, here is a USA document that more or less repeats the information, all be it that its writing about polyurethane.

Polyurethane Insulation Materials

Polyurethane is a closed-cell foam insulation material that contains a low-conductivity gas (usually hydrochlorofluorocarbons or HCFC) in its cells. The high thermal resistance of the gas gives polyurethane insulation materials an R-value typically around R-7 to R-8 per inch.
Over time, the R-value of polyurethane insulation can drop as some of the low-conductivity gas escapes and air replaces it. This phenomenon is known as thermal drift. Experimental data indicates that most thermal drift occurs within the first two years after the insulation material is manufactured. The R-value then slowly decreases. For example, if the insulation has an initial R-value of R-9 per inch, it will probably eventually drop to R-7 per inch. The R-value then remains unchanged unless the foam is damaged.
Polyurethane insulation is available as a liquid sprayed foam and rigid foam board. It can also be made into laminated insulation panels with a variety of facings.

Contacts | Web Site Policies | U.S. Department of Energy | USA.gov

They do of course produce sheets of the stuff covered on both surfaces with aluminium foil, this slows the drift as the leakage is only via the edges.

Sorry I cannot provide any more information, when I can, I will come back on this.
Perry.


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