Preliminary information:
City villa (built in 2019)
36.5 cm Poroton blocks without insulation, finished with silicone resin plaster
Garage (added later as self-build)
6.50 m * 9 m (21 ft 4 in * 29 ft 6 in)
24.5 cm Poroton blocks
1 interior wall with 11.5 cm Poroton blocks (4.5 inches)
Wood flat roof
Access to the house
The concrete slab will be poured for both structures together by the general contractor.
A sketch showing the garage’s position relative to the house is attached.
When planning to add the garage later, we initially considered building it with four separate walls.
However, we were recently advised to attach the garage directly to the house without a separating wall.
I actually prefer this option because it would give us about 25 cm (10 inches) more interior space.
Now to my question:
Where and how is the roof attached or supported on the house side?
Will the ridge beam (purlin) be omitted and the rafters fixed to the masonry using joist hangers?
Is that sufficient to carry the load?
Or is it possible to create recesses in the house’s masonry to install internal joist hangers so the rafters rest inside the house wall? (But there would have to be quite a few of them, which probably wouldn’t look good before building the garage, I assume.)
What other options are there?
I can’t just screw a ridge beam to the house wall with bolts the thickness of reinforced concrete, can I?
Yes, we will also discuss this with an architect and general contractor, but I prefer to go into such conversations with some prior knowledge so I don’t get sold a pig in a poke.
Thanks for your input.
City villa (built in 2019)
36.5 cm Poroton blocks without insulation, finished with silicone resin plaster
Garage (added later as self-build)
6.50 m * 9 m (21 ft 4 in * 29 ft 6 in)
24.5 cm Poroton blocks
1 interior wall with 11.5 cm Poroton blocks (4.5 inches)
Wood flat roof
Access to the house
The concrete slab will be poured for both structures together by the general contractor.
A sketch showing the garage’s position relative to the house is attached.
When planning to add the garage later, we initially considered building it with four separate walls.
However, we were recently advised to attach the garage directly to the house without a separating wall.
I actually prefer this option because it would give us about 25 cm (10 inches) more interior space.
Now to my question:
Where and how is the roof attached or supported on the house side?
Will the ridge beam (purlin) be omitted and the rafters fixed to the masonry using joist hangers?
Is that sufficient to carry the load?
Or is it possible to create recesses in the house’s masonry to install internal joist hangers so the rafters rest inside the house wall? (But there would have to be quite a few of them, which probably wouldn’t look good before building the garage, I assume.)
What other options are there?
I can’t just screw a ridge beam to the house wall with bolts the thickness of reinforced concrete, can I?
Yes, we will also discuss this with an architect and general contractor, but I prefer to go into such conversations with some prior knowledge so I don’t get sold a pig in a poke.
Thanks for your input.
Patkia schrieb:
I was once advised to cast a ring beam with channel rails around the garage, which rests centrally on a reinforced concrete column on the house side and is connected to the house masonry. This allows completely omitting the purlins, and the rafters can be fastened directly onto the channel rails.Regarding whether to use a ring beam or not, it is essential to consult a structural engineer (or a qualified planner or bricklayer). I personally prefer building with wood for private projects, which makes this unnecessary. My advice is also based on experience in timber construction; for solid construction with a wooden roof structure, have the load transfer checked by a professional, especially if you plan to carry out the work yourself.
@lastdrop
So this would basically be a combination of the two suggestions from dertill, if I understand correctly?
Anchoring the rafter plate to the masonry (if Poroton allows it) and then having a support underneath.
@dertill
Yes, as I said, that’s clear. During construction, a bricklayer will be present, and I will also contact a designer beforehand who can specify and calculate the relevant loads and requirements. I don’t want the house to collapse at some point.
As I mentioned before, I just wanted to explore the possible options first, so I’m not completely unprepared when talking with the general contractor or architect.
We’ve already been able to avoid several pitfalls and potential future costs by preparing thoroughly like this.
Building a ring beam is important to me intuitively, whether it’s strictly necessary or not. Therefore, the suggestion from my acquaintance to support this ring beam and use Halfen channels as the rafter plate also sounded like a potentially viable solution to me.
So this would basically be a combination of the two suggestions from dertill, if I understand correctly?
Anchoring the rafter plate to the masonry (if Poroton allows it) and then having a support underneath.
@dertill
Yes, as I said, that’s clear. During construction, a bricklayer will be present, and I will also contact a designer beforehand who can specify and calculate the relevant loads and requirements. I don’t want the house to collapse at some point.
As I mentioned before, I just wanted to explore the possible options first, so I’m not completely unprepared when talking with the general contractor or architect.
We’ve already been able to avoid several pitfalls and potential future costs by preparing thoroughly like this.
Building a ring beam is important to me intuitively, whether it’s strictly necessary or not. Therefore, the suggestion from my acquaintance to support this ring beam and use Halfen channels as the rafter plate also sounded like a potentially viable solution to me.
I don’t understand why the purlin should span freely if it is not anchored to the wall: what is the objection to a central support standing on the base slab, like in a carport?
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
@11ant
I’m not sure if I’m misunderstanding you or if maybe you misunderstood me.
I wasn’t actually considering just a cantilevered purlin, was I?
The discussion was really only about an anchor point or a support, right?
Or did you mean a support in the middle of the garage?
I’m not sure if I’m misunderstanding you or if maybe you misunderstood me.
I wasn’t actually considering just a cantilevered purlin, was I?
The discussion was really only about an anchor point or a support, right?
Or did you mean a support in the middle of the garage?
My solution would be along the lines of dertill’s suggestions in #4: a purlin in the position of the nonexistent house-side garage wall, resting on the front and rear garage walls and supported in between by a post on a joist hanger, similar to a freestanding carport.
Hanging each rafter individually on this side seems like a pointless hassle (and a Pyrrhic victory compared to just building the wall after all).
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
Hanging each rafter individually on this side seems like a pointless hassle (and a Pyrrhic victory compared to just building the wall after all).
https://www.instagram.com/11antgmxde/
https://www.linkedin.com/company/bauen-jetzt/
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