metal roof prep.

[silkcity]

I bought single wide , metal roof , I want to recoat ,the roof is peeling and flaking , I am scraping the peeling and flaking sections , should I scrape the old coating to the metal , the old sealant . aluminum . looks like one coat was used. as I scrape most times the metal shows , any advice on this subject . I want to redo the roof with aluminum roof coating . thx . ken

[Greg]

Follow the manufacturer's preparation for the coating that you are going to use. They vary between coating types.

Greg

[JD]

It is usually best to remove all the old sealants, but that is a big job sometimes. But if you have sealant that is axctully peeling away from the metal, the roof was not prepped right before the sealant was applied. This may mean that getting the rest of the sealants off won't be so tough. The most important thing is that the surface is stable and will not loosen or crack. I have been using a 9" grinder with a braided wire cup brush to remove the old sealants when necessary. I am going to try my Rockwell X2 Fein-like tool on the next roof.

Anyways, prep is being sure you the surface is clean and stable. Then I wash the coating area with solvent. If it is bare metal, I will use a roof primer like Super Primer from Ames Coatings or and undercoat product compatible with bare metal. If you are using an asphalt base aluminum sealant, as Greg said, take their recommendations.

[silkcity]

Thx Guy's for the advice , I did remove a lot of the old sealant most of it was not down to the metal . I found a handyman and he finished the job along with his two helpers , the next day I looked at roof and noticed there were small areas that were missed , openings by the flashing about 1/8 inch by 4 inches , and the j rails were not evenly sealed they did not use a brush on the rails ,they kind of used the squeegee for that , I have a roll of flashing , can I use this to patch the small areas I feel need it or should I use the leftover sealant to redo those areas ,I am not comfortable knowing that water can seep into and under the new sealant.

[JD]

A picture would help us give more specific advice. If this flashing is an awning flashing, it is not installed properly. Awning flashing should be under the drip rail on a metal roof or nose edge metal of a shingle roof. It can still be sealed, but will have a tendency to pool water.

Generally speaking, I would close that gap, if possible, with screws. Then if there is still a gap, it is best to use the roof fabric (looks like cloth toilet paper) with the elastomeric coating. To make the best seal, make sure there is not a void or air gap under that edge of flashing. if you can imagine painting on some sealant, then embedding the fabric into the sealant, adding more sealant on top of the fabric, cure then reapply, if this would leave a void behind the fabric, that is not good. I would fill the void first with a good butyl rubber or polyurethane caulk, to seal and fill in the void. Let that cure for 2-3 days, then go over the area with the elastomeric and tape thing. No air under the fabric.

On the drip edge, it sounds like it could use a better job of coating to me. When sealed properly, it will look sealed properly. I am really big on always using multiple coats to make the sealant last longer. It can be the difference between a recoat lasting one year, or 5 years.