Was ventilation required?
Hi
I have a commerical 15500 sqft per floor total 3 floors totaling around 46500 sqft building under construction that have low slopped flat roof that is almost flat with just a little slop the architect designed this roof with a TPO from firestone company that his TPO roof on first layer under TPO roof
there is A cover board under the TPO and under the cover board there is roof deck/sheeting and under the roof deck its insulated attic that has blown in fiberglass insulation. the builder had roof system installed but the roof was not sealed properly on most of edges and few vent areas. so almost for a month or so there was quite a bit snow on the roof that came and melted than after few weeks of snow here comes rain storm which leaked rain into edges of building on third floor. and after almost
month or so they found out that there is a condensation problem and due to that we have mold on the roof deck/sheeting builder is saying that its a faulty design architect did not put ventilation system in the attic and that caused the condensation. architect is saying that this type of roof assembly which is low slopped flat roof does need and ventilation because the chimney effect of ventilation doesnt work with the limited space in attic it have a insulated properly and builder have to keep moisture out of the roof cavity during the construction and make sure humidity level is less in the building and there is no air leakages from vents etc. which the builder did not and that caused the mositure problem and that is why there as a ice between roof TPO and cover board and a temporary heat was started before the roof was sealed that caused cold air for outside and hot air from inside also caused more moisture
that cased all this problem. So what i was wondering if there is anyway someone could help me out here was there any ventilation required in this situation? or was architect right and due to builders faulty practice of construction and roof/building and being airtight caused all the moisture to grow and made it to roof deck/sheeting that caused this problem?
If possible can some please call me so i can get some help
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Replies
Get your pros onsite and work out a solution. There are commercial dehumidifiers, there are pro clean up companies for the mold and there are temporary heat plants that do not add moisture while building.
You need better site supervision from whom ever is writing the checks to pay for this project.
Thank you AJ we already started working on it even tough architect doesnt agree ventilation is required due to this problem he created a ventilation system but both there is a substantial cost to remediation
of this problem and my insurance company denied the claim and builder is blaming faulty design saying if ventilation was there that is would not been a problem and other side architect is saying its not faulty design builder had bad practice during construction because temp heat was started before the building was sealed properly and also due to that snow and air leakages that was caused due to roof and being sealed this problem rise and there is no way i could pay extra i dont know who to blame if is could somehow get someones expert opinion that says to to blame with this problem so they can pay for the fix and not me since its not my fault
Deven,
If the insulation is on the attic floor (instead of above the roof sheathing, where low-slope roof insulation is usually installed), a low-slope roof assembly definitely needs ventilation -- and lots of it. The details as described are flawed.
For an in-depth discussion of what is necessary, see this article: Insulating Low-Slope Residential Roofs.
Thank you martin i did more digging and found out that the roofing company do have a layer of insulation called densdeck and then they have tpo membrane so in this case do you think architect is right and there is no need of ventilation as he stated and its not e design flaw and its construction flaw may be?
Deven,
We need more information.
1. What is your climate zone or location?
2. What is the R-value of the insulation installed above the roof sheathing?
3. Is the insulation in the attic installed in direct contact with the underside of the roof sheathing, or is it installed on the attic floor (with an air gap above it)?
Martin I am In Omaha,NE i think climate zone may be falls into zone 5
This is how the layout looks likes it starts from bottom this was designed by architect
first layer is one layer of 5/8" type c gyp bd.
second layer is 1/2" resilient furring channel @ 12" O.C
third layer is r-38 12" loose fill insulation was required by architect
builder installed insulation that is made of fiberglass material blown up insulation
4th layer is wood truss 24" o.c i dont know if this is on low side or not but i think it might be
5th layer is 15/32" plywood roof deck.
no ventilation system was provided by architect due to a low slop roof that have slopes as below
building is roughly 80 feet wide and it slopes 1/4:12 from east to west and its roughly 200 feet long and it slopes 1/2:12 from north to south and south to north every 50 feet
Then this roof system was designed by firestone and builder as follows and it called MAS-TPO
that shows deck type 1 wood 3/4" (19 mm)
than 1 layer of insulation that shows in insulation section and its called dens-deck 1/4" (6 mm) that has been mechanically fasten
than they have ultraply tpo gauge 60 mechanically fasten on top of that
first layer on top of roof deck
Deven,
That assembly won't work. Read the article I linked to to learn why.
Martin
I dont see the link here. also if this doesnt work who does that means architects design is wrong or roof materials are wrong? sorry architect is blaming builder and builder is blaming architect and no one wants to pay for the damages to fix the problem and asking me to increase my GMP even tough its not my fault
Deven
Deven, you need an experienced construction lawyer.
Deven,
Here is the link again: Insulating Low-Slope Residential Roofs.