Fixing shade sail to house wall - which screws?

[ringzer]

Hi,

I need to attach 2 X 3cm x 3.5cm Stainless Steel Pad Eye to the concrete wall at the back of my house to attach a rectangular shade sail

The company where I bought the shade sail have a decent installation guide here but dont specify how you should fix the pad eyes to the house.

The wall itself was built only a few years ago and if I remember correctly is a cavity wall with insulation in the middle. The width of the wall itself is about 30cm so the concrete block is probably the standard of about maybe 100mm I guess.

The shade sail will be also be attached to 2 X 125mm round wooden posts which have already been installed and will connect to these eye bolts which are fairly chunky.

The place I bought the pad eyes doesn't have much technical details but similar pad eyes here do. The width of the hole for screws are about 4mm wide so I'm not sure what type of screw I should use and if I should use a plug or not.

These masonry screws seem like what I'm after but they are 7.5mm wide so too big.

Any advice would be greatly appreciated as I'm hoping to fix the shade sail tomorrow, Thursday.

Thanks,

Ciaran

 

[Newboy]

To be honest, the fixings don't look adequate for a 20 m² sail. e.g. The installation guide mentions wooden posts but then specifies 48 mm/4 mm square profile angled steel posts.

If you're anchoring into masonry, it will depend on what type of block the wall has been constructed from. High density blocks would support sleeve anchors whereas lightweight aerated blocks would be better with resin fixings. Either way I wouldn't be using such small pad eyes - you won;t find a suitabe; fixing with such a narrow diameter.

As a guide, last time we installed something similar (although slightly larger) we used M12 turnbuckles into D shackles through welded anchor points.

Don't under-estimate the power of wind and rain!

A 20 mph 'breeze' could easily exert almost 1/2 tonne of force on the sail

 

[ringzer]

Thank you for the prompt reply.

To be honest, the fixings don't look adequate for a 20 m² sail. e.g. The installation guide mentions wooden posts but then specifies 48 mm/4 mm square profile angled steel posts.

The wooden posts specified are: "A wooden post at least 100mm diameter set in the ground (available here)."

If you're anchoring into masonry, it will depend on what type of block the wall has been constructed from. High density blocks would support sleeve anchors whereas lightweight aerated blocks would be better with resin fixings. Either way I wouldn't be using such small pad eyes - you won;t find a suitabe; fixing with such a narrow diameter.

Would a larger pad eye be better? Maybe this one: https://www.s3i.co.uk/10mm-Square-Pad-Eye.html

I actually found the details of what my builder installed and they are 4" Thermalite blocks. Would you recommend resin anchors in that case? Or what about Plasplugs for aerated blocks?

And how would I confirm the type of block/concrete I am dealing with? Should I just drill a pilot hole and see what level of resistance I get with the drill? Presumably thermalite is easy to drill compared to a tougher block.

What about using one of these fixings instead?

https://www.s3i.co.uk/eye-expansion-bolt.php
https://www.s3i.co.uk/commercial_eye_bolt.php

Presumably the commercial eye bolt could be fixed with resin?

 

[ringzer]

So having done some research, I think the following fixings should be sufficient. If someone can confirm, that would be great as I am hoping to install it all this weekend.

10mm eye bolt: https://www.s3i.co.uk/M10-Commercial-Eye-Bolt-100mm.html
Fischer resin fixing: http://www.screwfix.com/p/fischer-fip-300sf-polyester-styrene-free-resin-300ml/23386
12mm masonry drill bit: http://www.screwfix.com/p/erbauer-pro-masonry-drill-bit-12-x-150mm/78087 or http://www.screwfix.com/p/dewalt-12-x-150mm-extreme-2-masonry-drill-bit/43444

Presumably the 12mm hole is sufficient for enough resin to adhere to the 10mm bolt.

Given that the Thermalite block is 100mm thick, should I cut off 10mm so that there is a bit of the brick left so the resin doesnt just drop into the cavity? Or is it ok if the hole I drill goes right through the block? I have an angle grinder which should do the trick: http://www.screwfix.com/p/titan-ttb281grd-4-angle-grinder-230-240v/93905

Thanks,

Ciaran

 

[Chud]

Personally I'd be very wary of putting any kind of fixing straight into thermalite blocks as they're really soft - soft enough that you can push a nail into them by hand.

 

[ringzer]

Personally I'd be very wary of putting any kind of fixing straight into thermalite blocks as they're really soft - soft enough that you can push a nail into them by hand.

Can you suggest an alternative solution please?

The resin fixing I'm looking at stays it can be used in aerated concrete: http://www.fischer.co.uk/Home/tabid...tegory-1001076958/usetemplate-productdetails/ so it should be sufficient. Wouldn't 100mm of anchor inside the block provide sufficient fixing? Obviously a much shorter fixing has a smaller surface area binding to the brick but I would have thought a longer bolt would be sufficient.

As mentioned above, I found the work sheet from my builder to rebuild the back wall of our extension and it included thermalite blocks as well as bricks. Is it likely that the top and bottom of the wall were built with bricks and the middle portion is thermalite? The wall contains bifolding doors so there is a steel beam above these so seems likely that they would have built the wall above these in brick as a thermalite block would be too high.

 

[Burnerman]

Thermalite blocks are used on the inner leaf of a cavity wall......they are made from PFA (Power station Fly Ash) and there's no way you can get a strong fixing into them.
Concrete blocks are a different issue of course - if they are high density then Rawlbolts or whatever will be OK, or resin fixing otherwise - as per newboy's reply.
Is the wall rendered, by any chance?
John

 

[ringzer]

Thermalite blocks are used on the inner leaf of a cavity wall

So is the outer leaf of the cavity done in small bricks?

Is the wall rendered, by any chance?

Yes, it is. Does that give me out of a tricky situation?

The wall I am fixing into is about 5.5m wide with 0.5m of wall on one side and 1.5m on the other with ~3m bifolding doors in the middle. When we were refurbishing the house we had to effectively rebuild the extension and back wall, but some parts remained and should be concrete. The builders work sheet stated 40 thermalite blocks and 140 bricks (I have the sheet at home so can confirm if necessary) and I'm assuming the 140 bricks are for the top few rows of bricks above the steel beam. I'll check to see if I have any old photos from during the building work to see what is underneath the render.

Given that I am looking to fix into the top corners of the wall, it is probably more likely that this was existing wall and so not thermalite. Is it worthwhile drilling a pilot hole, maybe 2mm wide to see what is behind the render? Presumably if it is thermalite where I want to fix, then the drill will be like a knife through butter?

Thanks for all your help

 

[Tigercubrider]

Correct me if I am wrong but thermalite is grey, concrete is a yellowish (concrete) colour

So see what the dust is.

 

[Burnerman]

The wall behind the render will either be brick or concrete block.
Why not give one fixing a go, and see how you get on?
John

 

[Chud]

The wall behind the render will either be brick or concrete block.
Why not give one fixing a go, and see how you get on?
John

What he said - you could always try drilling a small hole to begin with and hold a dustpan etc underneath to catch the dust - if it's hard work to drill (needs hammer) then it'll be either brick or concrete block depending on dust colour...if the drill bit disappears into the wall as soon as you get past the render (and it's grey dust) then that's thermalite, if it's easy to drill and the dust is brown/yellow then you're probably in a mortar joint.

 

[Chud]

Correct me if I am wrong but thermalite is grey, concrete is a yellowish (concrete) colour

So see what the dust is.

Having just had a cavity wall done with blocks, bricks and thermalite I would say the thermalite is basically the same colour as the concrete blocks (grey)...but thats not an issue as (per my post above) drilling thermalite versus concrete is the drill bit will go through the thermalite with no effort or hammer required.