How to re-attach box gutter to rendered wall?

[tigerzen]

The box gutter has detached itself from the rendered wall. I tried a similar screw which was a little larger than the original but it didn't hold. It seems impossible to find the stud behind the render so I'll need to drill into render and blueboard(?). Are there special screws that will work in this instance, is there another way to attach this gutter?

 

[JacobZ]

Hi @tigerzen,

I reckon it's fairly likely that they have just screwed the end of the gutter to the render or blueboard, and that there is no actual stud behind that location. If you've tried a longer and larger screw without any effect, then this helps to confirm my suspicion.

My suggestion is to apply a bead of silicone to the back of the gutter, then use Ramset M4 x 8mm Hollow Wall Anchors to fix the gutter back in place.

You'll have to use a masonry bit to create a pilot hole for this anchor. If, while drilling your pilot hole, you hit something solid, like timber, we can always adjust the approach and install a Green Wall Plug, then screw it in place with the same screws that were used previously.

Let me know what you think and if you have further questions, please don't hesitate to ask.

Jacob

[tigerzen]

Hi Jacob, 

Thanks for the quick reply. There's no stud that I can feel, the drill easily drills through the render, looks like it will be Ramset anchors. The anchors your link refers to states plasterboard, I assume that they will be fine for outside use as well? Also, just a general question, on a rendered surface, how does one find where the studs are, internally I'd use a stud finder, look for nail holes etc., what do you do with a rendered surface?

[JacobZ]

Hi @tigerzen,

Hollow wall anchors will work the same in fibre cement and plasterboard as long as the wall material is around the same thickness.

It's not an ideal solution because hollow wall anchors aren't galvanised, so it will be a weak point in terms of rust, but in this situation, unless you could get access behind the rendered wall to install some timber, it's about the best you can do.

If you sprayed the anchor with a protective coating like this Dulux Metalshield Zinc Galv Spraypak before installation, then dab some silicone over the screw to protect it from moisture, this should help to protect against rust, but there is still a chance.

In saying this, it looks like the original screw they used was gold passivated, so it would be much the same as what was already there. 

Finding a stud would be much the same as indoors. A scanning type studfinder, if calibrated correctly, should be able to pick up studs in the same way. Personally, I prefer using a magnetic stud finder like this Trojan Magnetic Stud Finder to locate the screws or nails used to secure the sheets in place. Screws and nails mean there are studs behind the sheet.

Let me know what you think.

Jacob

[tigerzen]

Thanks again Jacob, I've got at least a couple of studfinders, I didn't know they could work through render. 

[JacobZ]

Hi @tigerzen,

It really depends on the quality of the studfinder. They might be effective, they might not, but higher-end models tend to perform better with things other than plasterboard. 

They work by picking up changes in density. Some studfinders might struggle because the render is denser than the plasterboard that they are marketed for and are typically used on.

That's why I prefer the magnet style of studfinder. As long as there is a screw or nail within about 30mm, they will react to it regardless of the density of the material in front of it.

I'd just give your studfinder a try and see how it goes. If you can't pick anything up, try a magnet style studfinder.

Let me know what you think.

Jacob

[tigerzen]

Just another question, I've noticed that the downpipes have all been installed with self-tapping screws as well and have come loose a little. Again they're installed into the rendered surfaces. Are there any other options beside the anchors, it seems there could be a few to replace?

[JacobZ]

Hi @tigerzen,

Unless there is something behind the wall that can be screwed to, then the anchors are likely your best option.

The only other thing I could think to do is spray some expanding foam through a pilot hole in the render, insert a Wall Plug while it is still wet, allow it to dry, then screw into the wall plug.

These aren't perfect solutions, but they should hold better than simply screwing into the render.

Allow me to tag @Nailbag, @R4addZ and @Noyade to see if they have any ideas.

Jacob

[tigerzen]

Thanks again Jacob, some interesting ideas and thanks for reaching out to the others.

[R4addZ]

Hi @tigerzen 

You can get Nylon cavity fixings and coupled with a Galvanised or good quality stainless steel screw you shouldn't need to worry about corrosion. The weight limit of the ones in the link below is 10 Kg so you may need to add more depending on expected load over the length of the gutter, they should be ok for the downpipes as the water doesn't particularly add much weight to the load as it is simply falling down the pipe.

https://www.bunnings.com.au/ramset-8-x-12mm-ramtoggle-4-pack_p2260486

As a guide, a litre of water weighs a Kilo so say over the length of 1 metre you expect a maximum of 10 litres in the largest down pour (I can't say these are real figures as I don't know the capacity of your gutters) each metre should have at least 3 fixings (you have to allow for the weight of the actual gutter). And don't forget to silicone over the screw heads to ensure no water can seep through or better still use rubber washers.