Ask Your Question

Angie's List Answers is the trusted spot to ask home improvement and health questions and get answers from service companies, health providers and consumers. For ratings and reviews on companies in your area, search Angie's List.

Top 30 Days Experts
Rank Leader Points*
1 kstreett 240
2 Guest_9020487 110
3 Guest_9190926 105
4 GoldenKid 100
5 ahowell 95
6 KnowledgeBase 95
7 skbloom 80
8 Guest_98024861 70
9 Guest_9311297 70
10 Guest_9400529 70

*Updates every 4 hours

Browse Projects By Category

Question DetailsAsked on 12/2/2015

on shingle garage roof, can metal roof be used effectively

Roof replacement. I want to install a sheet metal roof onmy garage. I would like to install it over a shingle roof.wii this be satisfactory

Do you have the same question? Follow this Question

1 Answer


Some contractors will put it over shingles, some will not. Personally, I consider it bad practice for several reasons -

1) you are not replacing the water barrier (tarpaper or synthetic membrane), so you are counting on THAT lasting another 30-50 years - a bad bet when that is your protection against water infiltration in the event of roof leakage, especially a flashing, valley, or ice damming infiltration

2) because you are not tearing off down to the sheathing, you do not know what its condition is - so you could be locking in decay and deteriorated sheathing that should have been replaced, plus if in poor shape the fasteners for the new metal roofing might not hold like they are supposed to in high winds

3) putting metal roofing over old shingles (or any other roofing) commonly results in distortions and ripples in the finished product that just plain look bad

4) could affect your warranty on the metal roofing - and even if not stated so in print, it gives the roofing manufacturer and contractor a VERY easy out in the event of a claim, by blaming any failure on problems in the underlying roofing, whether that is true or not.

5) if not taking off old roofing, you cannot do a proper flashing job at valleys and adjacent walls and chimneys and such, and cannot add effective ice and water shield at the eave areas, because those should go on the water barrier/sheathing, not on top of existing shingles or jimmied in under them.

For the maybe $$0.50-$1.50/SF difference in price for the tearoff and disposal, depending on your area, I wouldl not be pennywise and pound foolish. If it is worth doing, it is worth doing right. And several other truisms. Course, on a garage, if there is no living space above it or it is unfinished, the cost factor may weigh more than the possibility of leaks or appearance issues - your call, obviously.

Answered 4 years ago by LCD

Related Questions

Terms Of Use
Privacy Policy