Creating a gable roof out of a mansard roof

[Scout]

Hi Everyone,

I've just purchased a new home with a mansard roof which is pretty ugly. I'm looking for an economical way of creating a gable roof over the top of the mansard roof without removing the old roofing. Can I build a new rafter system over the top of this one. At the same time, I will remove the side part(the mansard) and replace with siding. If this is feasible, how do I tie the new ridge board and rafters securely to the new roof.

[marson]

rafters and ridge board really don't meet code to my knowledge. where rafters are used (rather than trusses) typically you will find a structural ridge, which is a beam supported by posts. this would have to be engineered (which could be done by the company that sells the beam). this would be a lot of trouble to retrofit since you would need to tear into your exterior walls down to the foundation as well as likely find an interior point down to a new footing.. if the mansard has a low slope, it might be possible to get a scissor truss to sit over the whole works (i'm just shooting from the hip here). otherwise you are looking at ripping the whole roof off and replacing it. no small matter.

[Jonny]

Can't be done. There's no way of tying the rafters to the top plate with the current roof in place. The roof is tied to the rafters, not the other way around.

[marson]

that part is doable with a simpson ST strap tie or something similar.

[JerryD(upstateNY)]

What would ever possess you to buy a home that needed a large amount of work when you don't know how to do the work ?

[Scout]

I'm simply looking at options at the moment. I thought the purpose of my posting here was to find out what can and can't be done and then take the required steps within my capabilities. I know how to install a new roofing system, I'm simply looking for a way to do it without disturbing the family too much and wanted to know if it could be done over the top of the existing one.

JerryD(upstateNY) wrote:

[Scout]