Roof plan needed? Whose responsibility?

5 years ago

last modified: 5 years ago

Hi, I will do house renovation and will add a new gable roof in the addition part and need to connect with existing roofs perfectly as drawn in architectural drawing (see pics below from three elevations). But the designer only provided the elevation, but no roof plan. I am worried whether the contractor could build the roof as drawn without roof plan. I asked her and she said structure engineer will show it in the report. But when I ask structure engineer, he said the roof framing is the standard practice of contractor, no need to provide anything to them.

I am confused and still worried whether it would be problem in construction phase. It seemed not easy to aline with the existing roof with right angle. How could the contractor build the roof without Need your advice! Thanks a lot!

Featured Answer

3onthetree

5 years ago

The basic purpose of the construction drawings are to convey the proper information for a 3rd party to build the structure exactly like it is envisioned. Usually a roof plan would include pertinent information that would be confusing if shown on a floor plan or elevation. However, a building could be built from a sketch on a napkin depending on the sophistication of the contractor. But if that builder has to ask for clarification, or needs further detailing, or misinterprets a situation, then more costs may be incurred by you. Some contractors actually look for drawing inconsistencies to screw you for more money. In other Owner/Contractor relationships, the drawings may be a formality and just enough to pass permit or solidify budget.

In this case there is a lot of information missing that you typically see. The AHJ may require certain drawings, like floor, foundation, roof, site, section, elevations, and plumbing isometric. If it is a simple structure and the AHJ allows it, a builder can use standard tables for spans and sizes without a structural engineer. If there is another critical piece of information you want followed, like matching an existing roof slope, the drawings should say exactly that.

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Comments (12)

PRO
Patricia Colwell Consulting
5 years ago
I guess my question is why a gable at all and could you at least give u s some idea of where the gable is planned on your house I do not see what makes snese with the elevation and the pic of your house . IMO your arhitect is the one to tie in the existing roof with the gable in the plan for the addition
PRO
Sabrina Alfin Interiors
5 years ago
If you're changing the roof line from it's current form, you'll need either an architect or a structural engineer to provide the correct structural drawings for construction. If this is a permitted job (and it should be) that's who you have to hire.
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formulaross20
5 years ago
The structural engineer is correct, an experienced framer will have no trouble framing this design.
HU-602114181
Original Author
5 years ago
The gable will be build for this two-floor addition part. Currently it's just a flat roof. Below is existing roof and what is in the future. All the roof facing to the backyard need to be rebuilt.
HU-602114181
Original Author
5 years ago
last modified: 5 years ago
Yes, Sabrina, the roof line will be changed, The architectural designer only provide the elevation, the structure engineer said that it's contractor's standard practice. What can I do? I am worried that the contractor could frame it without any dimension and drawing? See pic 3, the left roof of the gable need to be merged with existing roof with the same angle. And then the right side of roof line need to be on the same level of existing roof line in the right side of the house. It needs accurate dimension.
PRO
Sabrina Alfin Interiors
5 years ago
You have to hire a structural engineer to do the correct drawings.
PRO
Norwood Architects
5 years ago
Most architectural drawings sets for residential construction will include a roof plan which will show position of the roof, eave depths, overhangs, roof slope, etc. On our drawings we also not the bearing height of the roof (the height where the roof framing bears on the supporting wall). Depending on the jurisdiction building officials may also require a roof framing plan. Depending on the complexity those can be done by an architect, structural engineer or your lumber supplier but, yes, your designer should provide a roof plan.
HU-602114181
Original Author
5 years ago
Thank you for your explanation and advice! It's very helpful.
PRO
User
5 years ago
Your designer was insufficient. Renderings aren’t designs.
HU-602114181
Original Author
5 years ago
last modified: 5 years ago
Below is the feedback from the designer. Does it make sense?

"We are going to need to see how the original roof was framed to determine how to make the two roof lines line up.

We might need to use larger rafters on one side than is required structurally to accomplish this.

The contractor will be able to determine once the demolition has occurred and we can measure from the finished floor to the top side of the rafters if the two sides are lining up.

The structural engineer will also do a site inspection once everything is exposed to confirm the existing structure and what upgrades are necessary.

On a renovation, it is impossible to know everything before you start as some of the things you assume can be wrong so you leave flexibility to accommodate."
PRO
Charles Ross Homes
5 years ago
HI, Hu,

The structural engineer you consulted with said that a roof plan isn't required so I infer the building dept. won't require them for permit.

Your project is a simple addition to an existing home. The framer is constrained by existing conditions such as existing plate heights, cornice details, and roof planes. A couple of notes on the elevations should be sufficient to convey the designer's intent.