How to finish external corner with blueboard?

[sps42]

I have 4 fence pillars made of rendered blueboard that are in various stages of disrepair.  Photo shows worst of these.  As far as I can see they are sitting on a concrete footing.  The dimensions are 400x420x1050

I'm planning to try my hand at replacing them, starting with the one pictured.  I have to go with a solution that gives an end result that matches the originals as one is on the boundary and shared with the neighbour (who also has 4).

My thinking is to construct an internal frame from 90x45 H4 timber and clad with blueboard.  If possible I'd like to use a textured paint rather than a render beause I don't feel confident applying the render.  I'm assuming that if i don't render then I can't really use a render bead on the corners, so I want to know if there are other ways of finishing the corners that would work?  The internal frame would fully support each edge of blueboard, so could I get away with taping?  Or should I do everything up to the rendering and then get someone to do the rendering for me?

Any thoughts would be appreciated.

[JacobZ]

Hi @sps42,

Welcome to the Bunnings Workshop community, it is fantastic to have you with us.

Being outdoors, you would need to use treated pine, although H4 isn't 100% necessary. You could get by using 90 x 45mm Outdoor Framing H3 Treated Pine, and attaching plascourse to the bottom and sides of any timber that is touching the ground. This would work out a bit cheaper than special ordering H4 timber.

Unfortunately, taped corners would be extremely weak and prone to damage. This is not something I would recommend doing.

I spoke with the Dulux technical team about their textured paints, and they've told me that their textured paints can be applied up to 10mm thick, so in theory, you should be able to cover a render bead with a small nib, such as this Siniat 3.5mm nib 32 x 3000mm PVC External Render Trim. They do not have the testing data to guarantee it would work, but in theory, when you consider the application thickness against the 3.5mm size of the nib, it should at least cover the bead. In saying this, external corners are prone to damage, and I can't see textured paint on your external corners having the strength to last long-term. 

Personally, I think the best way to go would be to build the frames, fix them in place, attach the fibre cement sheeting and get them to the point where they are ready for render, and then either get someone in to do it for you, or give it a try yourself. 

There is some intricacy to rendering, but ultimately, it is just a process that, if you follow the steps without cutting corners, should be achievable. You might like to check out How To Render and How To Render Corners for an idea of the process and the materials and tools involved.

You should at least consider it and make an informed decision based on what you see. If you're not confident, getting a professional in for the rendering part of the project might be the way to go.

Allow me to tag @Dave-1 and @Nailbag to see what they think.

Jacob

[Dave-1]

Good Afternoon @sps42 

I do like you thinking of the way to replace the pillars, add in @JacobZ's suggestions and I dont see a problem.

I would keep an off cut of the blue board and have a go yourself at rendering and seee how it goes, for the minimal price you could end up with a nice boast If you dont like your work then you cna paint or get someone to render it but it will give you an appreciation on how hard/easy it is.

Dave

[sps42]

Many thanks @JacobZ .  Given your and @Dave-1 comments, I'll give the rendering a go.

Thanks again.

Simon

[sps42]

Many thanks @Dave-1 .  I'll give it a go!

[sps42]

Hi @JacobZ 

Just want to make sure that I've got all the info I need to start making the frames.  Do I allow 4mm of render to cover the 3.5mm render trim?  Therefore if I want a finished overall width of 420, the internal frame will be 397 (allowing 7.5mm of blueboard and 4mm of render each side)?

Thanks in advance

Simon

[EricL]

Hello @sps42 

My best advice is to double check your measurements once you have the materials in your home. When you begin to build your first frame, you'll have a better idea if any part will need adjustment. To remove guesswork, I suggest drawing your plan on paper and you'll see what your cut list will be and the amount of timber you'll be using.

Eric