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-   -   Painting the underside of the roof? (http://www.diychatroom.com/f9/painting-underside-roof-153905/)

Heidi Kellner 08-16-2012 04:27 PM

Painting the underside of the roof?
 
We have a large Cathedral style Attic in a Victorian home - dormers on all four sides, lots of gables and interesting angles.

Originally we wanted to spray the underside of the roof deck and condition the space, but we decided it was too risky, that leaks would be undetectable until significant damage incurred and that the house had an unfinished attic for 120 years - it can stay that way.

Sadly, it's one of the most fantastic spaces I've ever seen and all of us want to use it, me as an artist, my husband as a musician and my teenager as a teenager. Abandoning the risky idea of insullation I'm thinking of making it a useable space that would depend on the weather - a single window unit in the hot summer would make it possible to hang out up there and a couple space heaters in the winter - with the hottest and coldest times being just off limits.

My question is a weird one - in order to make the space neat looking I'd love to PAINT the underside of the room (this would include the old old 2x4 rafters, the old old sheathing (? wooden cross slats under the roof material) and the paint would also get onto the back of the roofing material as well (in this case it's some black material - tar paper?

Would the paint effect moisture in a negative way or would this be harmless?

Thanks!

OldNBroken 08-16-2012 04:44 PM

No, it's fine. Just keep in mind it will be a real mess of a room when it comes time for a new roof though.

joecaption 08-16-2012 07:58 PM

That would take one heck of an A/C unit to even put a dent in the temp.

Most attics have soffit venting and some form of roof venting or a gable vent. It would be like trying to cool an uninslated house with the windows open, and the oven running with the door open.

Windows on Wash 08-17-2012 07:45 AM

Quote:

Originally Posted by joecaption (Post 990513)
That would take one heck of an A/C unit to even put a dent in the temp.

Most attics have soffit venting and some form of roof venting or a gable vent. It would be like trying to cool an uninslated house with the windows open, and the oven running with the door open.

+1

That things is going to be burning through power like a nuclear sub at full tilt.

I would be surprised if it even makes a dent in the temps on a warm day.

Heidi Kellner 08-17-2012 10:49 AM

attics are hot
 
yes, i agree, we were up there when we had the heat wave in august and it was probably 110 + (F) up there. initially we wanted to insulate it and convert it into living space (1300 sq. feet floor space), vaulted cathedral cielings (2500 sq. feet of ceiling and gable wall space) - but with only 2x4 old old rafters there isn't enough space to insulate and too many conflicting ideas about closed cell foam, open cell foam, firing it out, roof leaks, ventilation questions - we just stopped pursing the idea to finish it off for now and just are thinking of making it a great space for when the weather is nice - until the insulation issues are resolved.....

tylernt 08-17-2012 02:39 PM

Painting wood in an attic is no problem (it's done all the time for mold remediation). I don't forsee any problems painting the tar paper either, both have similar moisture-permeability.

In order to heat or cool the space though, you've got to deal with the venting. Your goal is to isolate the room space for conditioning while still allowing full airflow from the soffit vents to the ridge vents. I wouldn't worry about insulating an occasional-use seasonal-use space because as you note, it adds a lot of cost, complexity, and risk. But simple horizontal furring strips across the rafters followed by drywall should let the rafter spaces breathe (to avoid moisture buildup) and let you condition the inside space somewhat economically. If you ensure that your drywall installation preserves full soffit-to-ridge airflow, I don't see a problem.

I have been wrong before though. :-P

Gary in WA 08-18-2012 01:41 AM

Remember this is an attic space, no painted drywall- fire-taped joints, smoke detectors; exposed wiring, exposed rafters, exposed insulation fibers floating around ?, with possibly "and a couple space heaters in the winter". This is why there are building codes- for your safety. Just add a heat/ignition source to an exposed light-frame attic for seasonal habitual living space.... keep up on your H.O. Insurance policy.

Gary
P.S. sorry to burst your bubble.

Heidi Kellner 08-20-2012 10:26 AM

insulating cathedral attic in old house
 
Just to clarify so you don't think i'm going to burn my house down and break codes. This is a totally unfinished attic with zero insulation (except some old loose stuff, think it's wool, under the floor and not much of that).

Ideally we want to finish the space off totally and move ourselves or our teenager up there. It's 1300 sq. feet of space.

There are currently ZERO roof vents. There are some vents along the floor at the edge of the roof line, but because of the many gables and odd angles they don't really vent all the way to the roof anyway. There is a vent in each of the two gable walls up high, old kinds that look like shutters.

We wanted to seal the whole space with closed cell foam, but are holding off on that for a number of reasons. 1. The roof was laid right down without plywood underneath first, so you can see the tarpaper inbetween the old wood that is on the outside of the rafters - sorry terminology of roof i don't know. So we are wondering how you possibly ever tear off a roof that has been undersprayed with closed cell foam. 2. If we spray with closed cell foam we only have a couple of inches unless we fir out our rafters, but 4-5 inches of CCF totals $10,000. 3. We are concerned about not being able to detect roof leaks with the CCF. 4. We don't have the venillation figured out for the CCF, but now it's sounding like we could use whatever HVAC system we end up using as the ventillation system? We haven't installed anything. There is nothing up there but 9 windows all around, a great vaulted ceiling and a cool old wooden floor.

Five insullation experts have looked at the space and we have five different methods proposed and all say it's the only way to go - so something isn't figured out right. We decided against open cell foam because it could mold and isn't very good on the R factor. Some tell us that 2" of CCF would really be plenty to insulate the space for winter and summers here on the border of a zone 4-5 area, but i'm not sure that's true. Any insight into what we could do to finish the space would be great.

Blondesense 08-20-2012 12:41 PM

Quote:

Originally Posted by Heidi Kellner (Post 992612)
...Any insight into what we could do to finish the space would be great.

Generally speaking, people on-site are more able to give you an accurate idea of your best options than a discussion online.

However, if you want to get the suggestions and discussion flowing, I would suggest posting some pics.

And don't forget to update your location. It matters.

tylernt 08-20-2012 01:24 PM

Quote:

Originally Posted by Heidi Kellner (Post 992612)
Ideally we want to finish the space off totally and move ourselves or our teenager up there. It's 1300 sq. feet of space.

Converting it to living space is different than making a space usable for occasional/seasonal activities. Living space is do-able, but you need permits and inspections (and your property taxes will go up).

Quote:

There are currently ZERO roof vents. ... There is a vent in each of the two gable walls up high, old kinds that look like shutters.
Ok, so you have gable vents. Better than nothing, but not ideal for a living space conversion -- you may have to do a "hot roof" and forgo all attic ventilation.

Quote:

So we are wondering how you possibly ever tear off a roof that has been undersprayed with closed cell foam.
I suppose if you kept the old bottom layer of tar paper to contain the foam, you could roll out more tar paper and reshingle over that.

Quote:

Some tell us that 2" of CCF would really be plenty to insulate the space for winter and summers here on the border of a zone 4-5 area,
CCF is about R-6 per inch. Here in Zone 6, it's recommended we have R-40 or more in the attic. That puts you at about 7 inches of CCF to exceed R-40, but perhaps CCF has other properties that allow it to be effective at only R12?

Windows on Wash 08-20-2012 05:19 PM

2" of ccSPF isn't cutting it regardless.

It would help mitigate the radiant heat in the summer but that is about it. Won't do much in the winter if the gables are still open and they need to be.

Attic floor needs to be air sealed in the meantime to help those gable ends try to keep up and prevent and moisture accumulation.


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