ᐅ Fixing the wall plate of a patio roof to the house wall

Hello!

I am about to build my terrace roofing. I am still unsure about how to fasten my 8x20cm (3x8 inch) wall beam to the house wall.

Regarding the house wall:
- 17.5cm (7 inches) aerated concrete
- 16.0cm (6.3 inches) insulation
- 4.00cm (1.6 inches) air gap
- 11.5cm (4.5 inches) facing brick

However, the fastening will not be done in the aerated concrete, but directly above the 6.5m (21.3 ft) terrace window (and the external roller shutter housing) in the lintel. Because the construction documents (we bought the house, not built it) do not specify the material of the lintel, I do not know whether I will be fixing the terrace roof into concrete, aerated concrete, or something else. The house is from 2012, so alternatives to reinforced concrete lintels were already available then.

For this reason, I am leaning towards the “classic” solution for fastening: M16 threaded rods, 530mm (21 inches) long, made of stainless steel grade A4, fixed with Fischer FIS V 300 T injection mortar. I would also use a 40cm (16 inches) long metal sleeve with a sieve opening.

First question: This is the standard solution for aerated concrete. Is it also appropriate if the lintel is made of concrete?

As a second option, I am considering anchor bolts of the same length. This would allow me to skip the injection mortar. However, I seem to recall that these anchor bolts are not approved for aerated concrete. So if the lintel unexpectedly is not concrete, I would be in a difficult situation.

Second question: Is my memory correct, or am I mistaken?

Third question: Can you suggest any alternative fastening methods?

Fourth question: Is the injection mortar I mentioned the correct one? There are so many variants, perhaps someone here is familiar with it.

Best regards

bra-tak schrieb:

Regarding the exterior wall:
- 17.5cm (7 inches) aerated concrete
- 16.0cm (6.3 inches) insulation
- 4.00cm (1.6 inches) air gap
- 11.5cm (4.5 inches) facing brick

For this reason, I tend to go with the "classic" solution for fastening: M16 threaded rod, 530mm (21 inches) long, made of A4 stainless steel, fixed with Fischer FIS V 300 T injection mortar. Also, a 40cm (16 inches) long metal sleeve.

This already results in a substantial 31.5cm (12.4 inches) non-structural layer, meaning the M16 threaded rod has to resist all bending forces here. If you don’t want to bond a threaded rod every 40cm (16 inches), I would lean more towards using M24.

bra-tak schrieb:

First question: This would be the standard solution for aerated concrete. But is it also suitable if the lintel is made of concrete?

Adhesive anchors can also be installed in concrete. The metal sleeve is usually only necessary in the area of the facing bricks, air gap, and insulation.

bra-tak schrieb:

As a second option, I have expansion anchors of the same length in mind. Then I could save the injection mortar. However, I recall that these expansion anchors are not approved for aerated concrete. So if the lintel unexpectedly isn’t concrete, I would be in trouble.

Second question: Am I remembering this correctly?

To my knowledge, expansion anchors or concrete screws of this length are not available from either Hilti or Fischer.

bra-tak schrieb:

Third question: Can you think of any alternative fastening methods?

The only alternative I can think of is to completely separate the patio roof from the building, using wooden posts in front of the façade.

bra-tak schrieb:

Fourth question: Is the injection mortar I mentioned above the right one? There are so many variants; maybe someone here is familiar with it.

According to the manufacturer’s website and approval documents, aerated concrete is at least listed as a compatible substrate.

Thank you. That already gives me a lot of pointers!

Simon-189 schrieb:

That already results in a solid 31.5cm (12.4 inches) non-load-bearing layer, meaning the M16 threaded rod has to resist all the bending forces here. If you don’t want to glue a threaded rod every 40cm (16 inches), I would rather lean towards M24.

I need to step in here again:
If I have both a sleeve and injection mortar in the area of the facing bricks, the threaded rod is also supported by the outer leaf there. So it transfers shear forces into the brick wall, which I believe is not problematic. Only compressive and tensile forces must be avoided with cavity walls.
If my reasoning is correct, you would still have 20cm (7.9 inches) of free threaded length between the brick and the masonry, but the bending load would be significantly reduced by the additional support.

bra-tak schrieb:

I just don't know whether to anchor the patio roof in concrete, aerated concrete, or something else.

Just do a test drill, then you’ll know for sure whether it’s concrete or aerated concrete. After that, you can consider the fastening options.

Simon-189 schrieb:

The only solution I can think of is to build the terrace roof completely separate from the building, supported by wooden posts in front of the facade.

That's how I would do it as well. In theory, the vertical supports could also be embedded into the insulation.