Levelling brick-built supports for decking bearers

Hello All.
The decking that pre-dates my purchase of my house has finally reached the end of its service life, being rotten within many of the boards and some of the bearers, underneath. I pulled it all apart over the last couple of day s and what I'm left with is three, parallel, brick-built supporting "walls" , running about 8m in length and with a span of about 4m (i.e.~1.33m betwee n each wall).
During removal of the old decking, after taking off all of the decking boar ds, I noticed that where the bearers sit on top of the brick walls, there w as quite a bit of packing material (slates, tiles and other assorted shite) underneath various of them. This packing material was presumably used to l evel the bearers and was required because the three supporting walls themse lves are not all at the same level, all the way along their length. The amo unt of correction required ranged from zero to a couple of inches, although it's probably worth mentioning that the less packing was used on top of th e outermost walls than the central one (i.e. the central wall deviates from the mean height to greater extremes than the others).
In an ideal world, if I had plenty time on my hands, I'd pull the whole lot down and build new brick supports for the bearers. Right now, though, the better option is to find a way to level the existing brick work. One notion that occurred to me is to clamp some shuttering against each of the walls, with the top of the shuttering at exactly the same level, all the way alon g all three. Then, I could fill the troughs created by the shuttering with cement/concrete, producing level upper surfaces to all three walls.
Is the shutter-and-fill approach sensible, or are there other, better ways of doing this? From previous experience, I tend to think that thin layers o f cement or concrete can show poor long-term adhesion an can be prone to cr acking and breaking-up in freezing weather. I'll probably stay living where I am for a good few years yet, so I'd rather not set myself up to have to re-visit this job any time soon.
Advice appreciated.
Regards.
Jim.
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On Sunday, 27 March 2016 08:31:27 UTC+1, Jim Walsh wrote:

e end of its service life, being rotten within many of the boards and some of the bearers, underneath. I pulled it all apart over the last couple of d ays and what I'm left with is three, parallel, brick-built supporting "wall s", running about 8m in length and with a span of about 4m (i.e.~1.33m betw een each wall).

ards, I noticed that where the bearers sit on top of the brick walls, there was quite a bit of packing material (slates, tiles and other assorted shit e) underneath various of them. This packing material was presumably used to level the bearers and was required because the three supporting walls them selves are not all at the same level, all the way along their length. The a mount of correction required ranged from zero to a couple of inches, althou gh it's probably worth mentioning that the less packing was used on top of the outermost walls than the central one (i.e. the central wall deviates fr om the mean height to greater extremes than the others).

ot down and build new brick supports for the bearers. Right now, though, th e better option is to find a way to level the existing brick work. One noti on that occurred to me is to clamp some shuttering against each of the wall s, with the top of the shuttering at exactly the same level, all the way al ong all three. Then, I could fill the troughs created by the shuttering wit h cement/concrete, producing level upper surfaces to all three walls.

s of doing this? From previous experience, I tend to think that thin layers of cement or concrete can show poor long-term adhesion an can be prone to cracking and breaking-up in freezing weather. I'll probably stay living whe re I am for a good few years yet, so I'd rather not set myself up to have t o re-visit this job any time soon.

The bits of slate/tile has the advantage that it's impermeable and will thu s prevent rising damp.
You can lay your new joists,temporarily position on bits of wood and the tw o outermost deck planks and secure them down with straps and then cement bi ts of slate under them. Or bits of Damp Proof Coursing.
The main thing to watch is that the joists are perfectly straight. And arrange things so that the grooves in the deck planks fall to one side by a few cm so the water drains off.
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harry wrote:

The grooves in deck planks are supposed to be at the bottom so that the water can dry between the decking and the bearers.
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No, because the places where there is currently only a thin packing required won't last very long done that way.

Packing does work if you don't want to do the bad walls again.

Not just in freezing weather.

I'd go the packing route again if you don't want to redo the bad walls.
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On 27/03/2016 09:26, Rod Speed wrote:

I have very little experience in brick walls but would it be better just to take the top layer of brick off (easy with sds + chisel) and then replace with adjusted layer of concrete when replacing top layer of brick.
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wrote

That would certainly be better than doing it without removing the top course of brick, but most walls have a different top course to the other courses. And there is no guarantee that the top course of concrete will stay on the top of the wall.
Personally I'd just pack it again if I wasn’t going to rebuild the walls.
Rebuilding the walls is entirely labour and the cost of the new mortar.
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On Sun, 27 Mar 2016 00:31:24 -0700 (PDT), Jim Walsh

Do a half way house and knock down the walls and replace with decking pedestals. obviously there is a trade off between price and convenience and time which only you can decide if it is worthwhile,
This is just one manufacturer http://www.wallbarn.com/products/roof-and-terrace-finishes/support-pads-for-timber-decking/
Ebay often has others at keener prices and sometimes some that some one has removed as they do longer want decking or a client has changed their mind.
G.Harman
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wrote:

Yes, and "only if *you* think it's better":-)
I have done exactly what you describe, and used a primer coat to promote adhesion, and also used it as an additive to prevent cracking in thin layers, as described on the label. It worked and has led up for over a decade in a harsher climate than yours.
A few bags of a very strong premix was enough, then a tiny tin of "adhesion promoter and crack preventer" or whatever it was called. It probably contains just PVA, but was a small tin and cheap. It would have been an expensive additive, only that with the relatively tiny amount of concrete and even smaller amounts of additive. (You could even look at a fiber additive, if really worried...)

No cracking here. And any settling of my foundation wall was in the past -- it has remained stable for over decade -- and you new wall may not be as stable.
If you can scrounge stainless steel offcuts: these make good and durable packers for the inevitable few mm it'll be off.
Thomas Prufer
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On 27/03/2016 08:31, Jim Walsh wrote:

If you want to do that .. use a Cementitious non-shrink grout rather than sand/cement I use grouts when laying level steel bases on concrete ... pack to correct height, put a frame around and then grout. The grouts are pourable, self levelling and expand slightly as thy cure
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