If you want to convert your old hip roof to a gable roof, then you should be prepared for some major changes in your roof. The hip roof will not have enough support to convert to a gable roof so you must add additional supporting structures to make the conversion possible. Before you can begin, you will have to work out how much space you need, and then figure out where you will need to place the support walls to turn one kind of roof into another. Then you can start converting the hip roof into a gable roof without placing too much stress upon the rest of the building.
Step 1 - Get Permission
Altering your hip roof to a gable roof involves some major structural changes to your roof. In order to do this, you will need to have permission from your local authority. Before you start removing the old hip roof, make some plans about how you intend the roof to be removed, how you will build up the new one, and where the internal supports will go. You will need to have some very accurate plans to show the building inspector before you will be allowed to proceed. Don't start building the new roof without this permission, as you may find yourself ordered to remove it by the local government.
Step 2 - Remove the Hip Roof
In order to make the conversion, you will have to remove part of the roof. Decide where you want the gable part of the roof to go and mark this down on your plans. Using a stepladder, remove all of the gutters, roofing tiles, and any other kind of roof furniture from the roof. Expose the wall beneath the roof. Go inside, and remove all of the wood and interior supports that held up the roof. You will need to replace them with more solid support.
Step 3 - Build up the Wall
You will now need to build up the wall which will support the roof. The wall should be built as high as the top point of the old roof, and will ideally be a triangular shape so that you can support the gable roof. When the bricks have been installed, ensure that you cover the surface of the brickwork with some caulking, and then cover the inside with a suitable plaster. Leave the surface to dry.
Step 4 - Install the Roof
Once the wall is in place, build timber supports for your roof tiles. Take the timber from the top point of your old roof, and then carry this over until it touches the top of the wall. Bring timber supports down, and nail to the edges of the support walls. You can then tile the roof as you would with an ordinary replacement roof. Ensure that the roof overhangs the wall slightly so that there is no access for water, and then install a layer of timber between the wall and the roof to ensure that rain does not enter the wall.