3 Ways on How to Join Two Roofs Together

Here’s a guide on how to join two roofs together if you ever needed it to improve and achieve your dream house.

It is difficult, if not impossible, to find a perfect home that both satisfies your personal taste visually and works absolutely functional. In this case, imagine its potential instead of being all wistful about it.

You can look at your new home for what it can become, not what it currently is. If the budget permits now, you are always able to add features such as installing the roof.

How to Join Two Roofs Together with the Same Pitch

Below are the steps on how to join two roofs together if they have a similar pitch:

Join Two Roofs Together with Same Pitch
  1. Determine where the two roofs will tie or join together. If they have the same pitch, then you’ll only require one framing type. Measure carefully to decide how many trusses that you need. To tie both roofs together, brace the upright and draw chalk guidelines on the shingles to mark the centerline of roof valleys, where they both will connect.
  2. Remove the facing boards, wall siding, and other obstructions of one roof’s end to tie it into the other—Mount trusses on one of the roofs.
  3. Install a ridge board, tie it to the first trussed roof, and ensure overlap between roofs. Once the trusses are secured, add other materials on the roofing systems such as roofing papers, shingles’ nails, and metal drip edge. Then add and trim the siding into the second roof’s end.
  4. Tie the second roof to the old one. Remove shingles and nailing on the chalk guidelines. Then cut jack rafters to connect the ridge board and valley board.
  5. Brace trusses on both of the roofs upright, and nail them to complete the roof framing.
  6. Finish by nailing OSB sheathing, metal flashing, metal drip edge, and overlap the new shingles between two joined roofs.

Joining Two Roofs with Different Pitches

Below are the steps on how to join two roofs together if they have different pitch:

  1. Prepare the area by identifying where the two different-pitched roofs will meet.
  2. Measure the length of the joined area. Pick the section where two edges will cross. Add 12-inch to the length.
  3. Prepare a flashing material in the width of approximately 12-inch.
  4. Put the flashing on the meeting point of both roofs. You must choose the higher one between the two instead of the lower one.
  5. Cut two pieces of lumber in the length that will fit the joined section. The purpose of these lumbers to seal the edge of both roofs.
  6. Place the lumber on the pitch of each roof. You should see that the roof edge and lumber edge are aligned if it’s done properly. Also, they must be placed under the flashing instead of above it.
  7. Stick the flashing to the roof so it will be secured perfectly.

Last but not least, put the shingles with the same looks. Use some to cover the flashing so it won’t be noticed.

Joining Two Roofs with Different Heights

The guide on how to join two roofs together in different heights is more or less similar to the steps on joining two roofs with similar pitch. The difference is only you have to fit rafter material or scrap or plywood at the back of the common rafter, in the section where both roofs meet.

If the heights of the two roofs are different, but the plate heights are similar, then you have to cut the tail of the valley rafter. That way, both roofs’ sheathings are supported in the intersection area.

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RoofLast is an experienced author and roofing expert. With years of practical experience in the field authored several informative articles on various aspects of roofing, including installation, maintenance, and repair