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You are here: Home / Archives for Roofing Underlayment

Roofing Underlayment

Best Approach to Hot-Climate Cathedral Ceiling

April 3, 2024 by buildingadvisor 1 Comment

Use of vapor diffusion port in hot climate cathedral ceiling.

Q: I have an unfinished space above our garage that we are converting into a flex space.  It has a cathedral ceiling.  We are in Houston, TX  so I am concerned about the heat and humidity in the space.  The west side of the space is sloping roof with soffit and gable vents along the entire length, so creating a baffle out of rigid foam is simple.  We have knee walls with … [Read more...] about Best Approach to Hot-Climate Cathedral Ceiling

How to Tile Over a Wood Deck

January 24, 2023 by buildingadvisor 5 Comments

Ditra tile membrane works as waterproofing as long as all joints and seams are properly sealed.

Q: I am redoing my wood floor balcony by sloping it, using a little dry pack  mortar and then waterproofing the surface using  Henry BlueSkin (peel-and-stick butyl membrane roof flashing). Can I apply thinset directly to the BlueSkin? I would like to use this as a waterproof barrier and cement the backer board on top of it.  Then set the tile on the backerboard. The photo … [Read more...] about How to Tile Over a Wood Deck

How To Install Two-Ply Roof Underlayment?

February 3, 2020 by buildingadvisor 4 Comments

Double layer roofing underlayment for tile roof

Q: What is the correct way to install a two-ply roofing underlayment? I was quoted a price on two-layered underlayment for my roof (Fontana G40 underlayment). I asked how much overlap he uses in his installs and he answered 2-4 inches. I was very confused as I have read your information and then confirmed with the TRI Installation Guide  (page 17) that there should be 18-19 … [Read more...] about How To Install Two-Ply Roof Underlayment?

Reuse or Replace Concrete Tiles When Reroofing ?

November 14, 2019 by buildingadvisor Leave a Comment

Tiles can be removed and replaced over new underlayment and flashing in a "lift and relay" job.

Q: Our original concrete tile roof, a little east of San Diego,  is around 30+ years old with a roof pitch of about 6 in 12.  My guess is that the underlayment should probably be replaced before adding solar panels. The tiles are in great shape with no cracks anywhere. The only problem is on the south end of the house where the fascia had some termites, so I cut off about a … [Read more...] about Reuse or Replace Concrete Tiles When Reroofing ?

Peel-and-Stick vs. Hot Mop For Florida Roof Underlayment

October 17, 2019 by buildingadvisor 29 Comments

Q: I have received proposals for re-roof of my house however each proposal calls for different underlayments with significant price differences. I live in Southeast Florida. I would appreciate guidance as to what makes the most sense. Thank you for your input; it is greatly appreciated! Proposal 1: - Install on Roof Deck Area: 2.1 One layer of 30# ASTM D-226 asphalt … [Read more...] about Peel-and-Stick vs. Hot Mop For Florida Roof Underlayment

Best Low-Slope Roofing Option

July 9, 2018 by buildingadvisor 14 Comments

Grace Ice & Water Shield offers good protection on low-slope roofs.

Q:  What is the best option for replacing a low-slope roof over an addition? We have a low-slope shed roof that was repaired with roll roofing as an emergency patch in 2014. We had ice damage which forced the roof repair, but because it was in the winter, only the lower half of the 23×12' area was repaired. The top half of the addition roof has asphalt shingles where it … [Read more...] about Best Low-Slope Roofing Option

Best Underlayment for Tile Roofs

October 5, 2015 by buildingadvisor 74 Comments

ASTM-rated roofing felt must comply with D 4869 or the older D 226 standard.

A: What is the best underlayment for a tile roof? Our house in Los Angeles is 25 years old. One roofer recommended removing the composite roofing tiles and replacing the old underlayment with 90-pound paper. Then they will replace the roofing tiles. Another roofer recommended the same approach, but with two layers of 30-pound felt as the underlayment. Please explain the … [Read more...] about Best Underlayment for Tile Roofs

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