Recent Q&A

• Wall assembly rebuild

  We have gutted a 19th century Italianate in Hudson, NY. The 2x4 wall bays are open to the backside of heavy clapboard siding with no sheathing. For insulation, I'm wary…

• Vapor retarders for double stud cellulose-filled wall assemblies

  Following up on last month's blog about building codes, am I correct that the code allows interior vapor retarding with latex paint on sheet rock? Also, does the vapor permeability…

• Would metal roofing (say Imperial Rib type profile) on decking and horizontal purlins work for venting a roof assembly with sealed fibrous insulation-filled rafter bays?

  的主要问题is whether the air space provided by the metal ribs would provide adequate air flow. If not, how about vertical 2X 'purlins', forming site-built insulation baffles that…

• How can I remedy a cathedral ceiling with fiberglass batts in unvented rafter bays that now emits a strong musty odor?

  Investigation revealed 3 problems: 1) no soffit vent; 2) insulation extending beyond the end of plastic rafter vents closing off the air channel up to the ridge vent; 3) no…

• Cathedral ceiling roof assembly

  The cathedral ceiling roof assembly on a recent addition to my house consists of vented fiberglass-filled bays with with an interior layer of 1/2" foil-faced polyiso under the 2x10 rafters.…

• Won’t double-stud walls have a condensation problem?

  Using exterior rigid foam solves thermal bridging and prevents condensation within the batts in the wall cavity. Double-wall construction also solves thermal bridging, but what about the dew point within…

• Rainscreen Venting

  I think I read in a recent string that rainscreen venting at the bottom, top, and around windows isn't necessary because the siding will let air in and allow drying…

• Roof Insulation Assemblies

  GBA blogs are filled with discussions of wall assemblies (insulation/vapor & air barriers), but I haven't found much on roof assemblies, particularly cathedral types. Assuming rafter construction, Is it best…