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Question DetailsAsked on 8/8/2013

Is it fair to expect the roofer to assure the airflow after the new roof is on the home?

Last Sept I hired a contractor to completely remove the existing roof and put a new roof on my home. The previous owner had roofed over a older roof and hadn't flashed the skylights correctly; so the roof had been leaking for the seven years I owned the home, however there was never mold in the crawl space.

I have since noticed mold in a crawlspace that I have under the roof. I've called the roofer, his claim is that it's not part of the job he was hired to do and the issue is in the soffits.

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5 Answers


This is sort of a typical no-win situation. If ensureing adequate airflow was not in the contract it makes it tough to prove who caused what. Since you call it a crawlspace rather than an attic, I guess you are talking a flat or low-slope roof.

Assuming the roofer did not change the soffits, it is possible that the previous 2-layer roof had enough airspace that it kept the crawlspace from getting hot enough to actively grow mold, which it is now doing with the greater heat from a single-layer roof.

Unless you can prove there is water coming through the roof now, you are hard pressed to prove it is the new roofers fault.

I presume you have attic ventilation - either active ventilation if flat or very low slope, or continuous ridge vent if pitched roof. Has anything changed about this between the old and new roof - like maybe new roofer did not put in a ridge vent that was there before ?

You have both a water source and a ventilation problem if you are sure the mold was not there before.

Unless the contract stipulated adequate ventilation to prevent overheating or mold or fungal growth, or called for replacement with aqdequate soffit venting, then you are probably stuck.

When you say you had it completely reroofed - do you mean sheathing too, or just felt and shingles or membrane or tar roofing ? If the latter, then it is possible the new conditions are promoting mold growth caused by water left in the sheathing by 7 years of leakage where the old conditions just were not right for it.

You also assume that the skylight flashing was the only leak source - there mighthave been one or more others, though a proper reroof job should have eliminated pretty much all of them.

I would find a reputable roofer to look at it and try to determine the source of the problem, then you can decide whether to try to go against the first roofer for repair costs. It might require mold treatment to kill what is there, then watch to see if it regrows (and where) to try to track the water source. Mold thick enough to see clearly will NOT grow in an attic or crawlspace without an on-going moisture source - either leakage, moist air from the house or a utility system, or trapping of very humid outside air in a poorly ventilated or unventilated confined space for an extended period of time.

Answered 7 years ago by LCD


The only thing I could add to LCD's answer is I have seen sloppy roofers forget to cut the tar paper at the ridge vent if you have one. Other than that if you did not have mold before the new roof you should not have it now.

Answered 7 years ago by ContractorDon


This roofer took all the decking off down to the rafters and replaced it with new deck, paper and architecht shingles.

The crawl space is only on the south side of the house and it's from the soffits in to a 3.5 foot knee wall upstairs. The otherside of the house has no such space, not sure if there is mold there.

The current roofer's inspection states no leaking, it's all condensation. Not sure how someone who doesn't know much about roofing would know to specifically ask that there be airflow.

Do I follow up with a new roofer? or do I need a siding company to put in new soffits?

Answered 7 years ago by Guest_9968112


Sounds like you may have a Cape Cod of house. If the roof is insulated it is possible that the "proper vents" a baffle that is installed between the roof deck and the insulation was either removed during the demo or never was there. If the roof is insulated and there is no air flow over the insulation that could be the cause. Another thing that can happen is a sloppy demo crew that lets debris fall into the soffit area and does not remove it causing existing soffit vents to be blocked, if there were any. I my opinion the roofer should have seen there were no vents in the soffit prior to starting the job. In this day and age most people do shop for the best price and though you probably would not include it in you bid if others are not you should advise the owner of the situation and offer it as an add on and if declined by the owner a disclaimer could be added. If this roof has been leaking for seven years with out a mold problem it would make me think there was adequate venting before new roof. You may be able to check for venting on the side with the crawl space by going in there on a bright day and shut the light in crawlspace off and look for daylight along the eves. As to the ridge vent being installed wrong sorry to say the only way to check that would be to remove a section to see if the plywood was cut to allow air flow and tarpaper as well.

Answered 7 years ago by ContractorDon


Followup and a bit of explanation to what Contractor Don said:

The eave vent baffles he talked about install like this to endure air flow over the insulation, between the rafters - see where labelled "baffle".

and look like this - may be plastic or waxed cardboard, stapled in a trough or U (ronded, angled or squared-off U) to the rafters to prevent the insulation from blocking the eave air flow - also knows as soffit baffles or eave air troughs -

On a different thing he said:

What he said about perhaps the tar paper not cut or the sheathing not cut for the ridge vents - you may not have to take one off to check. If you have access to see the underside of the peak of the roof, there should be a slot cut by removing a strip of sheathing along the length of the ridge, about 3-6 inches wide on each side of the ridge centerline, leaving an open slot the length of the ridge through the sheathing. Over that, the tarpaper or roof wrap (like Tyvek housewrap) should have been cut away (or never placed). You should be able to see the underside of the plastic ridge vent - either a low peaked plastic "cupola", possibly with baffles, or might be made of plastic mesh like a mesh dish scouring pad on a large scale. In all probability, with no lights on in the attic on a sunny day, you should be able to see at least some filtered sunlight showing through the vent. If you can see that along most of the length of the ridge (last 3' usually left intact for sheathing strength against blowoff), and from the outside you can see a mesh or dark cavity or overhang up under the ridge shingles (roof not shingled over solid at the ridge), then the ridge vent should be good.

A way to check if it is working, if you can get at the underside of the ridge peak, is to check for airflow - wet your finger and check for an upwards breeze toward the ridge vent, or take a sheet of saran wrap or a very light fabric and hold it up tight against the top edge of the sheathing between two rafters during the heat of the day or early evening when the attic is hot - it should sway towards the ridge vent. I would EMPHATICALLY recommend you not create smoke (unless you use a bulb syringe and baking flour) to check for airflow - if you accidentally started a fire up there that would not help matters AT ALL.

If you cannot get at the underside of the vent, then try the dust or saran wrap onthe outside of the vent at the roof ridge on the outside in calm conditions when it is hot in the attic still - there should be a slow but distinct flow out of the vent, at least on the downwind side.

Answered 7 years ago by LCD

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