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How to fasten awning to fibre cement weatherboards?

Hi Community!

I've recently began painting the exterior of my house. I've removed the awning (pictured) to paint/restore it and paint the weatherboards around it easier.

I expected it to have been fastened to the frame of the house, but to my surprise there were these long screws that came out, and there was no house frame behind them. Is it safe to assume hollow wall anchors were used?

Not sure if relevant, but the holes in the weatherboards were around 12mm in diameter, much larger than the screw diameter.

What would be a suitable set of fasteners to use when I go to re-mount the awning?

The awning itself is around 20-25kg at most. I will likely be re-attaching it to the same place (so I'll need to make the the 12mm holes aren't an issue for whatever fastener I will be using). In the absolutely worst case I can move the mounting points elsewhere and just fill the old ones (if the 12mm holes are an issue). There are a total of 4 points where it was fastened.

Thanks!

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JacobZ

Hi @denisl,

When you removed the fixings, did you hear a nut or something similar fall behind the weatherboards?

I ask, because these are bolts, not screws, meaning they have to have been tightened into some kind of threaded fixing such as a nut or anchor. I can't say I am aware of what anchor would have been used, nor would I recommend an anchor in this situation, but it may prompt some ideas if we can work out how exactly they were attached previously.

The problem isn't so much the weight of the awning, it is the uplift that is possible if a strong breeze gets underneath the awning and the fact that they are attached to the weatherboard which is a non-structural element. Over time, these strong winds can weaken the connection to the weatherboard, and eventually cause something, whether it is the weatherboard or the fixing itself, to break, and the awning to fall and potentially go flying.

Unfortunately, the only solution I can comfortably recommend is to attach the awning to the framing of the house, as this would ensure it is attached to a structural element that is at very low risk of failure under excess wind loads.

Unfortunately, you might have to speak with a carpenter or handy person for assistance with this one.

Allow me to tag our knowledgable members @Dave-1, @Nailbag and @R4addZ to see what they think.

Jacob

Nailbag

Hi @denisl

Looks like the awning was most likely fixed your toggle fasteners like these. But this heavy duty type would take the weight far better. But you may have to trim the bolt heads accordingly with a hacksaw or angle grinder They would allow you to utilise the same holes though you might need to make the weatherboard side larger to accommodate the toggle.

Nailbag

Dave-1

Good Evening @denisl

Yeah those bolts are for toggle bolts, thats why the hole is large so they butterflys can be folded back and pushed through. Then they pop out and when tighted up they spread the contact area over a larger area.

Option A replace like for like or with the ones @Nailbag has suggested. I like the toggle bolts as they have always worked well for me. Tho you are fixing to the weather board not the frame which is a bigger concern.

Option B Purchase some exterior plywood, Then cut into strips that fit from where the support brackets are to the edge of the window. This becomes the backplane that the awning is screwed to. The reason for the width is you will pick up the strcyual supports around teh window for sure this way. So the timber is screwed to the studs through the weatherboard, then the awning is screwed through the supports into the plywood. Best of both worlds this way.

Dave

denisl

Hello guys,

Thank you so much for your replies - very informative!

To answer @JacobZ 's question, I did not notice if anything fell as I undid the fastener, but I am quite certain it was a toggle anchor of some sort. I had not considered the possibility that the awning is not fastened to the frame at that point, so I undid them all before giving it a second thought.

Thank you for raising the concern re: fastening to the weatherboards only! I will endeavor to re-attach it properly.

On @Dave-1 's idea about using plywood, where would the plywood be fastened to? Two studs (one near window, and next one over) per side of awning? I like this idea, just trying to visualise the details.

I had also considered possibly adding a noggin into the frame, by pulling off the FC boards where the fasteners would go. I've never pulled off boards before, so not too confident in my abilities but the noggin part would be fairly easy. The boards may also have asbestos (early 80's house), so I'd have to get it tested first. Any insight on how easy / hard it might be to pull off the weatherboards?

Cheers guys!

Dave-1

Afternoon @denisl

Heres a sketch.

Pink is plywood
Green dots are screws to secure.

Larger green dots are for securing to the plywood.

Dave

JacobZ

Hi @denisl,

Due to the age of the property, it is possible they contain asbestos, and it is never worth taking the risk. I'd definitely suggest that you have them tested for asbestos before you do anything that could damage them.

I can't say I've done it myself, but removing and reattaching the same weatherboards, especially fibre cement ones, is unlikely to be an option because there's an incredibly high likelihood they will snap in the process. If you could source an exact match, then you might be able to add some noggings, then replace the weatherboards, but it would be tricky and I'd likely suggest you'd need an experienced carpenter's assistance.

Let me know if you have any further questions.

Jacob

denisl

Hi guys,

Thanks so much for the info, very helpful!!

@Dave-1 thank you for the diagram, really appreciate it :)

Cheers,

Denis

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