Replies

1. 
   Piffin | Jan 26, 2006 12:43am | #1

   If you use foam to buffer the noise DO NOT put it directly under the metal like that. The fasteneres used in the metal need steady pressure against the firm substrate of the wood to maintain the neoprene seal and keep water out.

   I would deal with it by using 1" foam under the cieling joists, then strapping, then two plies of sheet rock. Regular batts or cellulose or BIBBs above the faom.

   best way would be to spray foam insulation to the bottom of the plywood sheathing tho - that is more expensive.

    

    

   Welcome to the
   Taunton University of Knowledge FHB Campus at Breaktime.
    where ...
   Excellence is its own reward!

2. 
   4Lorn1 | Jan 26, 2006 12:53am | #2

   I think the noise issues with metal roofs is exaggerated. Even without a ceiling of insulation I have only heard one or two roofs that made much noise in even the heaviest summer rain. Both were very flat shed roofs.

   Might have to do with the angle the rain hits or the relative stiffness of sheets applied flat and the thickness of the sheet metal. Both were thin utility grade corrugated roofs as I remember it.

1. 
   user-97872 | Jan 26, 2006 01:13am | #3

   Let me add a bit of info that I should have added to my original post.

   The roof of this building will be a 16/12 pitch using scissors trusses on 24" centers. The roof itself will be solid sheeting, felt paper, and metal roofing.

    

1. 
   Piffin | Jan 26, 2006 01:38am | #4

   The type of truss makes no difference, except with ref to insulation and venmtilation. A cathedral cieling is harder to control moisture and venting and shows condensation problems more. Tht makes the sprayed on insulation a higher priority. Corbond is big out your way. it will pay for itself in energy cost and customer satisfaction.I live under metal roof. We hear nothing onm main floor. The upper floor bedrooms - the kids or guests are aware that it is raining , but no noise to complain of. 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

2. 
   scottthebuilder | Jan 26, 2006 04:00am | #5

   What about a layer of an Ice & Water Shield like W.R.Grace. self adhesive underlayment. We use it in Florida under metal, slate, clay, and cement tiles, even asphalt shingles. We cover the whole roof deck with it to help stop wind driven rain in a Hurricane. Also if you loose some roofing in a storm it will stop most if not all leaks. I think it's around $20 a square.

1. 
   Piffin | Jan 26, 2006 05:13am | #8

   That would be a good bufer that would not compromise the roof 

    

   Welcome to the Taunton University of Knowledge FHB Campus at Breaktime. where ... Excellence is its own reward!

2. 
   JohnSprung | Jan 27, 2006 03:12am | #13

   That sounds good.  Maybe a good idea to put a bond breaker between it and the metal for expansion/contraction.  Red rosin paper is used that way under copper. 

   My roof is 3/4" ply, SBS base sheet, rosin paper, and copper.  In a hard rain, you can go up in the attic and hear it a little.  But down in the house, the rain on copper sound is overwhelmed by the rain on the skylight.   

    

   -- J.S.

    

3. 
   Luka | Jan 26, 2006 04:19am | #6

   Dangit, Scott beat me to it !

   =0)

   I was going to suggest Grace Ice and Water Shield as well.

   However, my suggestion is that you turn the metal roofing over, and apply the grace to the metal roofing.

   Then turn it back over and apply the metal roofing as usual.

   ---

   Rudeness is the weak man's imitation of strength. ~~ Eric Hoffer

4. 
   brownbagg | Jan 26, 2006 05:02am | #7

   I got metal roof on tar paper then 5/8 plywood. then two feet of cell insulation then drywall. I cannot hear it when it rains. Besides, the sound of rain on metal roofs is what makes them so great

   . 2+3=7
5. 
   IdahoDon | Jan 26, 2006 05:50am | #9

   We always had the roofers install twine zig zagged across the surface of the roof to quiet it down in the strong winds.  It's commonly viewed as a better install if done that way in the windy parts of WY/CO.   I always wondered if the same thing doesn't help deaden the sound of rain as well.  With the thinner roofs, the twine will telegraph if walked on carelessly, but otherwise doesn't seem to affect anything negatively. 

   My vote would go with the sprayed foam, which is a fantastic way to go with cathedral ceilings since you also don't have to vent the roof and deal with blowing snow melthing in the ridge vent and dripping into the living space.

   Cheers,

   Don

1. 
   Matt | Jan 26, 2006 06:44am | #10

   >> We always had the roofers install twine zig zagged across the surface of the roof to quiet it down in the strong winds.  <<  I'm not getting the pic here - or maybe a really weird pic... :-)  Where exactly does the twine go?

1. 
   IdahoDon | Jan 26, 2006 06:56am | #11

   Where exactly does the twine go?

   It's stapled on top of the felt paper, in 12" zigs, or are they zags, across the entire surface of the roof.

1. 
   Matt | Jan 26, 2006 01:38pm | #12

   OK - I gotcha...  I had this weird pic in my mind of string on top of the metal roof...