One story house without anything other than one Peak. Currently shingled. Roof has minor leaks that are resulting in mold on the ceiling in various places. Contractor is discussing leaving current roof, putting furring strips down or one buys and then adhering the metal roof to that

. 1 he is saying it will save time and money versus the tear off. There is currently one layer of shingles. If you were seeing isolated spots of mold on the ceiling oh, would you recommend this being done?

Of course the other option is to tear off the shingles and re shingle but that is not preferred over metal.

Is there any problem doing this since mold has been seen to come through? My concern is that even if the roof is covered would there still be mold growth on the sheathing that is currently there Andover time take away the integrity under the metal?

If the roof decking is sound and the shingles are not curled up, we regularly lay metal over shingles down here.

You MUST use an underlayment or you will void the warrantee. I use synthetic membrane roofing underlayment. You can also use 30 pound (not standard 15 pound) tar paper. I greatly prefer the synthetic stuff. It's stronger and safer to walk on while screwing down the metal.

Moss on the outside of the roof will reduce the life of the shingle and it will create a slippery work environment for the roofer. Bleach will kill the growth as will getting rid of the water source and drying it out.

If moss is growing on your ceiling, then you have a serious leak and additional work is required.

So because some mold on ceiling. Require shingle tear off?

Yes it is a ranch

If you have mold / mildew growing on the inside ceilings, water must have been leaking in for awhile. Once the source of water is stopped, it should be easy to deal with the stains.

If their is moss growing on the actual roof, I've found the easy way to treat it is to spray Wet & Forget on it then rinse with a hose.

IMO it's never a good idea to lay a new roof over an old roof especially one that has been leaking for some time. If this is a property you're planning to keep then all you're doing is just kicking the can down the road.

Steve does bring up a valid concern.

If water has been getting in for that long, the 3/4 inch thick plywood could be compromised. If this has planks instead of plywood, it is a bit more forgiving.

I typically don't strip off the old roof to put on a new metal roof. But I typically don't have mold growing on ceilings - although if it is in the bathroom it could be from lack of ventilation.

If your sheeting is damaged, you really have to strip off the shingles. If it is a flashing leak, then maybe you might be able to save some money if the wood isn't rotted out.

you use the term shingle but don't define the type. the roof you describe is called a gable roof. asphalt comp? wood shake shingles? either way, i wouldn't go over unless it is simply unavoidable as a stop gap and not with a permanent roof like metal or laminated asphalt comp

i've installed hundreds of roofs as a contractor and the best practice is a full tear off and proper repairs to framing, starter boards (eaves) and roof deck. a full tear gives a good look at the structure. metals roofs last a LONG time and you can have a very secure roof for a VERY long time knowing the structure was properly prepared and made rain tight for the next decades...