Limited Attic Space, no insulation, need help fast

Generally you would want to have vents along the eaves of the roof, then vents at the peak of the roof and a clear path for the air to flow as pictured on the following web page.

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So best to have this type of air flow and to not block that air flow with insulation.

So far as the knob and tube wiring, I would have it all replaced with romex if it is acceptable to cover the romex in your area with insulation, then not to worry about that.

So far as the recessed lighting, no matter what the label says, these can get *very* hot and damage/melt the insulation on the wiring. I would have the electrician verify that these are wired with appropriate new high heat rated wiring. Then I would also be sure to not cover them with any insulation so the heat can dissipate.

So far as how much insulation, with the current high energy costs, I would add as much insulation as possible to the attic and also add the roof top insulation. It will probably be worth it in the long run. I don't know what your heating and cooling costs are, but if you want to lower them, then consider the cost of this work -vs- the cost of added insulation.

And so far as spray foam around the existing electrical boxes for ceiling lighting, again these can get to be quite hot as heat travels up. I would re-wire with appropriate new high heat wiring and ask the local building inspector what is allowed. I have seen these where the heat from a regular light bulb has caused the insulation on old wiring to fall to pieces leaving bare wire (was not high heat rated wiring). Personally I would tend to want to leave a little ventilation above these just like the recessed lighting.

Overall, your area may require a building permit to install insulation. Good idea to get a permit and discuss your plans with a local building inspector before the work is done, then have it inspected after the work is done. If no permit is required, might want to see if you can pay a building inspector to check it out in their spare time or something - make suggestions as to what would be best.

Reply to
Bill
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Hi - Kelly. I'll make my comments inline below...

Good idea here. Your climate may see less benefit and a longer payback period but it couldn't hurt.

Ventilation is very important in attics and will prolong the roof life and eliminate rot, etc. I would make sure there is some airspace between the roof sheathing and the insulation AND that there is a way for air to enter and exit.

Given that this is a flat roof, there are products that can be added on top for insulation. they are not 1/2" thick, they are about 3 or 4 inches thick urethane. Here is one of many

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If I insulated the 'attic' I would leave airspace and add vents.

That pipe may or may not be adequate. There should be a place for air to enter and exit under the entire roof.

That would be best answered by a heating AC guy. Are you getting hot or having trouble staying warm or both ? You may never see a payback or ROI. You could in a year. Too hard to tell.

Its about R5 per inch. They are most likely talking about a 3" product. make sure they are then that price may be OK. its definitely not for a 1/4" product.

They are cheap - Just get an IC rated can if you are adding the insulation and venting. Do not mess with non-IC in an insulated area.

Don't worry about it - Very little, if any, will leak out.

So - To sum it up. If it were me. I would add a 4" ridged foam on top of my roof sheathing before I had my new flat roof installed. Before it was installed I would have some sheathing removed so my K&T wire could be looked at. If the insulation was crumbling off I would have it replace with romex. If it was fine I would leave it alone. Maybe at this point I would have my recessed light installed. I can use the one I have because I'm not putting insulation in my 'attic'.

Our advice is free, take it for what its worth.

Reply to
No

The fusing current of 12 ga copper wire is 235 amps...

Nick

Reply to
nicksanspam

I'd replace all the knob and tube wiring with romex while you have access to that area. I'd only use IC rated lighting. I also would not fill the entire space with insulation. There should be air space with vents for a way for air to enter and exit above the insulation. This keeps the temps down and prevents moisture problems. Plus in your area with milder climate, you can get by with less insulation.

Reply to
trader4

I beg to differ on a couple of points. Cellulose insulation isn't flammable. There are a lot of borates in the formula that make it impossible to ignite. Grab a handful at Home Depot and put a torch to it. I have. Won't burn. Foam is flammable, but there are formulas available today that aren't like they were 10-15 years ago. Foam burns, but the smoke, though colored differently than the smoke from the wood (less water vapor in the foam) the chemical make up of the foam is no more toxic than the smoke from the treated lumber. That is a fact.

Also, most foamers will build a drywall high hat and surround it with mineral wool and foam around that. Mineral wool doesn't burn at all.

But, this application seems more of an air sealing application than a insulating application given that the extremes in temp aren't a factor.

Of all the options, what is the best air seal choice? Not the fiberglass, that's for sure.

abi

Reply to
abi

You are right that it is insulated. Of course by now a lot of it is not all that insulated.

However you are at least a little off on the wire gauge thing. I am not quite old enough to know if they originally required or used larger gauge wire for a circuit. The stuff I have worked with did not. In fact it used smaller gauge wire. The physical separation and the ability to dissipate heat allowed it to carry the additional current per wire size.

Reply to
Joseph Meehan

The additional physical separation of the wires allowed a greater ability to dissipate heat and that allowed for the greater capacity.

Reply to
Joseph Meehan

My house is wired with knob and tube and it is a bigger gauge. However, don't take my word alone for it:

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Dimitri

Reply to
D. Gerasimatos

I have heard health warnings regarding loose glass fibre floating around, so I'd avoid "chop"! There may be roll-on matting of an alternative synthetic material available to you, but that requires access. Look at foam in-roof, or under sheeting, again.

Reply to
zenboom

How about the p2000 foam insulation:

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For 1 inch, installed with seams properly taped and an air space like you have, you can get close to R-40. Yes... 1 inch... r-40. It's expensive but great for limited space. A number of the timber framers around here are starting to use it since it's so useful for limited space areas. The 1 inch of p2000 gives better r-value than the regular rigid foam they used to use. I understand it's been used commercially for some time and is just now getting onto the residential market. From the literature it seems it gets it's high r-value by addressing radiative and conductive heat along with a vapour barrier all at the same time.

- Scott

Reply to
Scott

Who did the wiring job? It looks like a bunch of 4-year old Special Olympians were turned loose in your attic.

Better get the wiring corrected before you insulate.

Reply to
Oscar_Lives

If it were my house I would replace the crappy old knob and tube wire with something good like armored cable and have foam put in so you can get good R value with enough space left open for venting (add vents if you need to). I would also be tempted to replace the in house light fixtures with new ones that could support some serious weight so that I could put in ceiling fans if I wanted to. You really need to get rid of that old wiring for insurance purposes.

Reply to
scott21230

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