Ask Builders
Add question
  • Questions
  • Tags
  • Builders
  • Help

Is fiberboard under the roof really necessary?

Asked 5 months ago.
Active 5 months ago.
Viewed 683 times.
  • fiberboard
  • roof
0

We are planning the following roof/first floor construction (urban villa with a hipped roof):

— Concrete ceiling instead of wood construction on the upper floor

— Insulation on the concrete ceiling

— No roof insulation.

Now our general contractor has offered us a 35mm thick fiberboard (possibly an underlayment board?).

Reason: If the shingles are damaged in a hurricane and it rains, our entire attic will not be under water.

The cost of this fiberboard is $4,000.

What do you think? Is this board necessary?

asked 5 months ago
Author avatar
304The Red Gorilla
Author avatar

Answers

2

Well, you do have the advantage of being able to store more temperature-sensitive things there. Whether the one is worth the extra cost must be considered.

answered 5 months ago
Author avatar
76Roger Alv
Author avatar
1

Then you can consider directly insulating the roof, if it's already being worked on so diligently. Otherwise, leave it alone.

answered 5 months ago
Author avatar
55AamerJZ
Author avatar
1

I would also prefer to properly insulate the roof and leave the upper floor ceiling insulation out.

answered 5 months ago
Author avatar
145Tami B Knop
Author avatar
0

Three levels of rain protection?

1. brick

2. substrate

3. wood fiber insulation board

Water is silly when it comes through the roof, but I don't see it as a risk. For protection against summer heat, 35mm doesn't do much good, but it's better than nothing.

answered 5 months ago
Author avatar
1Andor Xanthopoulou
Author avatar
0

But assuming this (unlikely) case happens.... the water will still go somewhere.

We have the same roof. The ceiling is insulated, the roof is not insulated. We only have fiberboard over the ceiling insulation so we can access the attic. After the storm, we're just checking to see if everything is still okay.

answered 5 months ago
Author avatar
21QuinnYa
Author avatar
0

For that kind of money, I would have thought of much better. The benefit is close to 0.

answered 5 months ago
Author avatar
56Builder Sunny
Author avatar
0

The underlay can then be omitted. Double makes no sense.

answered 5 months ago
Author avatar
116Ramonda Valiente
Author avatar
The underlayment would also be omitted, should you decide to use the wood fiber boards.
– Prospero Perez  5 months ago
Answer this question

Related

  • What vapor barrier option to choose for the roof?
  • Concrete vs clay shingles
  • Birds' nests under the roof – what to do?
  • What are your thoughts on a curved roof over a house entrance?
  • What is the price of cold roof insulation with Ruberoid?
  • A 20 degree single pitch roof with no attic?
  • What are those stains on the roof beams?
Log in Join
Privacy Policy・Terms of Service