We are facing a renovation of the upper floor, and I am working on a spec for how I want the construction of the load-bearing parts to be executed.
I have a constructor who will calculate more in-depth on this when the time comes, but I would like to have some feedback/input on the construction already (see images below).
Notes:
The main idea is to get a larger, furnishable living room with an open ceiling to the ridge in the section that constitutes the living room area, both in the existing house body and the new dormer.
The collar beams are cut in the part that will be open to the ridge.
The existing roof trusses seem weak compared to newly built houses, so I am hesitant to hang anything on them (which seems common in new builds). To take up the load from the dormer's exterior walls, I thought of reinforcing the trusses up to the ridge beam with 45 x 225; perhaps this is not necessary?
Dimensions:
Existing roof trusses:
Top chord = 50 x 150 (2" x "6)
Bottom chord = 75 x 200 (3" x 8") (same as the floor between trusses)
Struts = 50 x 100 (2" x 4")
Collar beam = 50 x 150 (2" x "6)
Roof pitch 38°
Roof covering:
Raw wood panels, concrete tiles, both house and dormer.
New construction:
Longitudinal ridge beam = Glulam 90 x 405 (Taken from a table based on a cathedral ceiling with a free span of approx. 9 m) length 4.8m
Transverse ridge beam (dormer) = Glulam 90 x 270 (Taken from a table based on a cathedral ceiling with a free span of approx. 4 m) length approx. 4m
Exterior wall frame (dormer) 45 x 145
Dormer rafters = 45 x 145 free span approx. 2 m (to be doubled for more insulation)
Reinforced trusses on either side of dormer = 45 x 225
Pillars = glulam 90 x 90 (preferably) or 115 x 115 if needed.
All attachments in the load-bearing construction are intended to be done using suitable nail plates/brackets and the like.
The main load is intended to be directed down via pillars to the heart wall/exterior wall. The pillars in the center of the house are placed near pillars on the lower floor but not in a straight line (see images).
Heart wall/exterior wall/pillars (lower floor) are laid on reinforced concrete bases that can be considered completely stable, the beam in the heart wall = IPE 200 with support every 4 meters.
Hope someone has some opinions/comments/suggestions to offer - thanks in advance!
Might be a bit vague, I can specify my questions a bit:
- Is the construction with beams something common or does it look odd?
- Is removing the collar ties risk-free? I can't see any function for them anymore when everything rests on the ridge beam..?
- Do the rafters need reinforcement on either side of the dormer?
- How is ventilation usually handled for the air gap in a cathedral ceiling open to the ridge? Ridge vents?
- Reasonable (not optimal) insulation thickness in the dormer's roof? (I want to maintain a good ceiling height).
- Anything else I haven't considered?
It's been a while since you wrote about your thoughts. How has it been going? Have you built the dormer yet and did your engineer have any objections to your design suggestions?
Nicely done sketches
Best regards // Simon
Click here to reply
Vi vill skicka notiser för ämnen du bevakar och händelser som berör dig.
