Anyone familiar with construction? Roof Venting? Foam Insulation?

[Roger Bacon]

I have an older cape cod, I want to re-finish the second story.  The roof rafters are 2x6's, which doesn't allow room for proper venting, insulation, and drywall.  I could use furring strips, but wonder if a non vented, spray foam system might be better?  The Foam would give me an R-Value of 35.75.

What do you think?

[Tapeworm]

Galv metal furring channel is an excellent product.  You'll get no screw pops in your drywall and it can be installed on clips (rather than direct fixed to the bottom of the 2x6s) which will allow you to plane your ceiling true and give a dead straight wall/ceiling angle and apex.  It will also accomodate seasonal framing movement to a far greater degree than if drywall is affixed directly to the roof framing and allow you easy and cheaper electrical modifications.

Expanded polyurethane provides the best R value, far as I know, followed by polystyrene.  For a small job like this I would think you'd do far better moneywise to install sheets or simply glass batts yourself than to pay a contractor to bring his foam spray rig.  US contractors might be hurting tho, in which case you can sub the whole thing without it costing too much.  They're not fools though and will cut corners if you cut price.

PM me if you want further advices.

[Roger Bacon]

Galv metal furring channel is an excellent product.  You'll get no screw pops in your drywall and it can be installed on clips (rather than direct fixed to the bottom of the 2x6s) which will allow you to plane your ceiling true and give a dead straight wall/ceiling angle and apex.  It will also accomodate seasonal framing movement to a far greater degree than if drywall is affixed directly to the roof framing and allow you easy and cheaper electrical modifications.

Expanded polyurethane provides the best R value, far as I know, followed by polystyrene.  For a small job like this I would think you'd do far better moneywise to install sheets or simply glass batts yourself than to pay a contractor to bring his foam spray rig.  US contractors might be hurting tho, in which case you can sub the whole thing without it costing too much.  They're not fools though and will cut corners if you cut price.

PM me if you want further advices.

Thank you, really appreciate the advice!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!  Getbiggers know everything!!!

This area is about 550 sqft, but the roof is very steep/high so it's a decent amount of area I believe.

The only reason I was leaning towards the foam is because of the fact that the roof doesn't have any proper venting, and due to the design of the house I can't really figure out how you could even install soffit vents.

[Tapeworm]

I haven't used a foam spray rig but they strike me as a tool for a bigger scale.  Maybe they're in common use for smaller jobs in the US tho.  You could probably cover your roof area with only 6 or 7 bags of R3.5 (I think that's a USA R35) glass batts, which would fit in the 6" cavity after another inch or so of furring channel.  It's probably worth finding out what a bag covers and costs, and comparing it to a spray foam quote.

I assume you're in the northeast?  I live an an area where venting and mold aren't a big deal so I'm not up to speed on the benefits and downsides of venting.  I would imagine that an airtight roofspace would lead to issues however, since you're always going to get differing humidity loads in the roofspace with changes in day/night temp, frostline, etc.  I've never heard anyone advocate an unvented roofspace.  Premium US homebuilders seem to poo-poo houses which don't breathe.

If you want to DIY I can give you detailed step by step instructions on everything except plumbing and electrics as far as interior trade works go.  Naturally, I can't speak to your local regulatory requirements.

Just get me that date with your mom.

Edit: I'd imagine that gable and soffit vents could be retrofitted but hard to say without photos.  My expertise is more limited when it comes to exterior works.

[Tapeworm]

http://www.getbig.com/boards/index.php?action=profile;u=55522

Ask this dude about installing venting.  Evidently, roofing is his specialty.  Oh brother.

[Roger Bacon]

Just get me that date with your mom.

lol

The house was originally built without any roof venting, but all these idiots around here are always going on and on about how you need venting to keep condensation off the bottom of the roof deck and to take heat out.  I think I might just go with the metal furring channel, and fiberglass.

[sync pulse]

lol

The house was originally built without any roof venting, but all these idiots around here are always going on and on about how you need venting to keep condensation off the bottom of the roof deck and to take heat out.  I think I might just go with the metal furring channel, and fiberglass.

Well they can be correct...

[Tapeworm]

As I said I'm no expert on roof ventilation but it's probably not a one size fits all thing.  There are going to be differences in roof and gable wall construction from one house to the next.  Your place might be getting plenty of airflow through gaps in the siding.

Step one would probably be demolition, if you're already sure that you're going to remove the existing ceiling and install a new one.  That will allow you to inspect the roofspace for signs of rot and mildew caused by poor ventilation.  Then you can make a decision based on what you find as well as local advice.

Bear in mind that the furring channel will drop the ceiling height by at least an inch, and more if your ceiling plane is dictated by sagging rafters, and if it's an older place they are almost certainly up and down.  This drop can present problems if you've got windows near the ceiling.  If you have dormer windows, which is likely in a Cape Cod style, the framing, hanging, and finishing will be trying for a DIYer.  Keeping true lines where the raking and plumb planes of the dormers intersect the raking plane of the ceiling can get hairy if the framing is running out.  And remember you'll be dealing with a new wall/ceiling junction, so if the walls are papered or textured then they might be coming out, which means the baseboards go, the stariwell becomes an issue, etc.

All I'm saying is: be sure you can't just live with a new coat of paint before you embark on this.  And be sure to cost the project from the most hopeful scenario through to the apocalypse now scenario before taking a wrecking bar to anything.

[Roger Bacon]

As I said I'm no expert on roof ventilation but it's probably not a one size fits all thing.  There are going to be differences in roof and gable wall construction from one house to the next.  Your place might be getting plenty of airflow through gaps in the siding.

Step one would probably be demolition, if you're already sure that you're going to remove the existing ceiling and install a new one.  That will allow you to inspect the roofspace for signs of rot and mildew caused by poor ventilation.  Then you can make a decision based on what you find as well as local advice.

Bear in mind that the furring channel will drop the ceiling height by at least an inch, and more if your ceiling plane is dictated by sagging rafters, and if it's an older place they are almost certainly up and down.  This drop can present problems if you've got windows near the ceiling.  If you have dormer windows, which is likely in a Cape Cod style, the framing, hanging, and finishing will be trying for a DIYer.  Keeping true lines where the raking and plumb planes of the dormers intersect the raking plane of the ceiling can get hairy if the framing is running out.  And remember you'll be dealing with a new wall/ceiling junction, so if the walls are papered or textured then they might be coming out, which means the baseboards go, the stariwell becomes an issue, etc.

All I'm saying is: be sure you can't just live with a new coat of paint before you embark on this.  And be sure to cost the project from the most hopeful scenario through to the apocalypse now scenario before taking a wrecking bar to anything.

Thanks for all the input!  I guess the major reason this is bothering me is because of the shitty R-11 insulation that is currently in the ceiling.  So I plan on adding the other 8 inches or so to fit r-34 or whatever it is.  I can just feel all the heat going straight out the roof.    

I'll post pics when I get this project going.  I believe my friends and I can accomplish this with all our bro-science. 

[Tapeworm]

There's also loose fill blow in insulation.  The contractor should be able to suggest ways of getting in, discuss venting issues, and examine the suitability of the ceiling for the load.