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Attic Vents and Insulation

I'm buying a house built in 1927 with an asbestos tile roof that has no attic insulation. I'm planning on insulating the attic floor with fiberglass insulation, but there is just one vent in the roof. Will I require additional roof vents, and if so, how do I install additional vents without walking on the roof and breaking tiles?

Re: Attic Vents and Insulation

A skyhook will come in handy.

Depending on how much you weigh, you can walk on the roof being sure to step only on the overlapped sections of the tiles.

Asbestos roofs are tricky to work with as cutting the tiles generates dust which can give you lung cancer. The next option is to remove one whole tile and cover that area when installing your new vent. The next option is replacing the entire roof, adding ridge and soffit venting at the same time.

Re: Attic Vents and Insulation

Other good options:

- A few dormers. They require cutting the roof and rearranging the tiles (A job for an experienced roofer).

- Vents between the joists and the rafters.

Re: Attic Vents and Insulation

IMHO you should NEVER walk on an asbestos tile roof, and should leave any modifications of such a roof for vent installation on the tile sections to pros who are accustomed to working (usually) with slate roofs or asbestos tile roofs; slate roof workers alway use (as HR notes) hook or sky hook ladders that will keep the worker's weight off the roof----anyone walking on an asbestos tile roof will cause hairline cracks (often which can't be seen) that will create leaks and a real nightmare.

I question whether you should buy this house in the 1st place since you have found out it has an asbestos roof---if the roof is in excellent shape without any cracks, leaks, or stains (unlikely it is in "mint" condition), then it will probably last for years without need for replacement; however, you should be aware that REMOVING such a roof to replace with asphalt or other roofing will usually mean involvement with OSHA for disposal of asbestos hazardous materials and a considerable expense to you; this should be a bargaining point in settling the purchase price with the current owner after you have gotten an estimate on the expense of replacement costs.

If the house sale has already gone through, you will have to live with the reality of having an asbestos tile roof; as previously noted, if the roof looks ok & doesn't leak, then it will probably last for years without any major problems.

In regards to attic insulation (R40 insulation is recommended for attics) and venting----why not get a quote from an insulation co. for BOTH jobs; most insulation companies will do the vent work as well; you can also negotiate this issue with the seller for a reduction of the sale price if the deal has yet to be finalized.

At least you found out at THIS stage that you are dealing with an asbestos roof-----most buyers are kept ignorant of this fact by the seller & real estate agent until after the deal is finalized on the pretext that neither one knew about the asbestos slate, & assumed "it was a slate roof"; remember, the real estate agent represents the SELLER'S interests, NOT the BUYER'S interests.

If you eventually DO decide to handle this as a DIY project, it may be best to consider either passive or power fan (static or power assisted) GABLE VENTS on both sides of the house, calculated according to the standard formula used to sizing the vents according to the number of square feet of attic space you have (see sites below for calculations)---this would keep you off the roof and prevent any damage to the asbestos tiles.

After clicking onto & reading the 1st site below, click onto the other You Tube videos presented for additional video sites, especially one entitled "How to calculate and install attic ventilation" Pt.1 and Pt.2 by Iris Communications; or Google this phrase to calculate the amount of venting in square inches you will need for your building.


Re: Attic Vents and Insulation

Attic fans are intended to cool hot attics by drawing in cooler outside air from attic vents and pushing hot air to the outside. However, if your attic has blocked soffit vents and is not well-sealed from the rest of the house, attic fans will suck cool conditioned air up out of the house and into the attic.

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