Decking wall refurb and wind break

[pudding]

Hello,

 

I built a wall around our decking a few years ago, and attached to this I fixed some posts and strips of wood to act as a windbreak as we're in a pretty exposed place. This windbreak worked well and helped make it a more usable place.

 

 

However, the paint on the wall needed a bit of a refresh as it had staining and marks running down it, so i stripped off the posts, and slate capping on top so i can clean it all and repaint. The paint had also started to peel in a few places where water was able to get in behind the paint at the top of the wall where the paint met the slates, which aided the fungal growth there and stains. 

 

 

My current plan is to clean all the walls with a jet washer, (ive already sprayed them with some anti fungal spray too), then paint the walls with some new Sandtex masonry paint, making sure the paint go up on to the top of the walls, before I refix the slates on top, the idea being any water that then runs over and under the slates on top cant get behind the paint any stays on the surface. Refix the slates using full bed of this on the wall and also back of slates - https://www.screwfix.com/p/mapei-keraquick-wall-floor-rapid-set-flexible-tile-adhesive-grey-10kg/5769P?tc=FA5&ds_rl=1249416&gclid=Cj0KCQjw8qmhBhClARIsANAtbocYz28jIVSSOuiULvRUlQ55bQwn00Y4KV1XOsrguJlu405gOmiMmycaAoo0EALw_wcB&gclsrc=aw.ds rather than concrete as I'd done previously, which hopefully will also stop water getting under the slates.

 

Next is the wooden posts and wind break. At the mo I'm not too keen or putting the posts back where they were, as they leaving the marks on the wall, and I'm wondering if there is a better solution to protect this area from wind? Any ideas welcome. If nothing else comes up, I'm thinking maybe just mount the posts on top of the walls this time rather than being fixed to the wall face, but then I'd prob need some horizontal wooden joists between the posts for support and strength?

 

Cheers for any comments and tips.

 

[Onoff]

1 hour ago, pudding said:

At the mo I'm not too keen or putting the posts back where they were

 

Slip some 1/4" thick plastic washers over the bolts before refixing the posts. That'll give a clearance and stop the staining.

[Dave Jones]

before putting the coping stones back on run a length of dpc along it, cut it so its 5mm wider than wall to shed the water. 

[pudding]

Thanks for the comments so far. Good tip with the plastic washer/spacer between the posts and wall, will give that a go I think unless any better ideas crop up.

 

With the DPM idea, are you thinking run the DPM along the whole length of the wall edges? I'm not sure how you're thinking of sealing/fixing it to the wall/slate here to stop water getting onto the wall or possible behind the paint, unless I still paint up onto the top of the wall under and before the DPM is fixed on top? I've got some CT1 or stick like sh!t which could do the job for DPM-wall fixing. It did also cross my mind to fix all the slates down with this too, would make a nice waterproof seal between slate and top of wall/paint im thinking? Just it'll take a few tubes of the stuff and it's not the cheapest.

 

Edited April 6, 2023 by pudding

[Conor]

Second the DPC idea from @Dave Jones

 

what happens is water soaks through the coping and down through the middle of the wall, then out the sides through the paint. The reason why your paint is failing. 

 

You want a full width DPC, trimmed back to the width of the coping. You can get 400/450mm wide rolls from anywhere really. To lay, put a thin bed of mortar on top of the wall, lay the DPC down, more mortar on top, then the coping, and angle your coping 1⁰ or so to shed water. Trim back the DPC when cured. A bit of waterproof plasterciser in the mix won't do any harm. 

Edited April 6, 2023 by Conor

[Dave Jones]

1 hour ago, pudding said:

Thanks for the comments so far. Good tip with the plastic washer/spacer between the posts and wall, will give that a go I think unless any better ideas crop up.

 

With the DPM idea, are you thinking run the DPM along the whole length of the wall edges? I'm not sure how you're thinking of sealing/fixing it to the wall/slate here to stop water getting onto the wall or possible behind the paint, unless I still paint up onto the top of the wall under and before the DPM is fixed on top? I've got some CT1 or stick like sh!t which could do the job for DPM-wall fixing. It did also cross my mind to fix all the slates down with this too, would make a nice waterproof seal between slate and top of wall/paint im thinking? Just it'll take a few tubes of the stuff and it's not the cheapest.

 

 

im really just following the NHBC spec for capping a parapet wall, albeit you wont need the cavity closer.

 

https://nhbc-standards.co.uk/7-roofs/7-1-flat-roofs-and-balconies/7-1-17-parapets-and-guarding-to-terraces-and-balconies/

 

 

[Onoff]

I'd render the top of the wall with a water proof render, have a slight fall outward.  I'd then stick the slate to that. A line of black CT1 between each slate.  Also a ring of CT1 around your stud before you push the packing washer on.

[Canski]

I would use some paving slurry when you bed the slates back on. 

[pudding]

I've still got a load of black jack dpm paint that I used at the bottom of the wall left, so I could paint the top of the whole wall in that and waterproof it that way? I'll be putting that Mapei flexible tile adhesive I've already got on both back of slates and top of the wall as you would for a normal decent tiling job.

 

With the packing washer idea, with that keeping the post off the wall I'm thinking it would no longer be very sturdy, as the bolts and nuts (there were 2 for each post) were clamping the post against the flat wall giving it strength. Will a little washer won't it then be pretty wobbly as it'll only be clamped against the much smaller surface area of the washer?

[pudding]

Update! Pretty much all done now. So, order of works was - scrub&wash walls, repaint 2 coats including painting up into top of walls slightly, then use left over render to render wall tops sealing edges of paint hoping to prevent any water getting behind it, outdoor tile adhesive used then to bed slate capping and a piece of DPC in between each slate beneath the mortar line (the mortar line between each slate was where the worst water run-off marks were leading to algae), then pieces of slate used behind each post, also sanded/re-oiled, so it stood off a few mm from the wall, plus bottom of posts trimmed so any water will drip slightly away from the walls. Decking scrubbed, jetwashed then re-oiled, very satisfying job! Time will tell to see how long this all lasts before I need to clean it all again.