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mattyb · Dec 28, 2012, 06:16 AM

Apologies for the strange questions, but I'd like to know some terminology. I've build a wooden terrace (2 in fact). Think that you call it decking in the US. Its not built on a concrete slab.

What I've done, after consulting various French D-I-Y sites, is remove a layer of earth. Used a geo-textile (to avoid grass and weeds growing) and then covered that in sand (heavy stuff that doesn't wash away). Then I flattened it out and put concrete tiles at strategic points to support the joists. The joists are 2x4 with about 12 inches between to form a large square with cross-supports every so often. Then I screwed on (using screws for the outdoors) the treated wood 'planks'. This was all fairly easy, except for the leveling of the sand, which was a real bitch. Since these two terraces please Mrs. Mattyb, there are other areas that she would like doing.

Is there a trick or is there a better method of building a wooden terrace that will not be on a concrete slab? I know that you can use the circular supports that are adjustable but this wasn't recommended for planks, more for the large tile-like pieces of wood that you can get. We didn't want those.

So, whats the advice on leveling the sand, is there another method and please don't hesitate to inform me of the correct terminology.

reader50 · Dec 28, 2012, 09:11 AM

Why level the sand underneath? A deck is supported by the upright posts, usually 4x4s. Which should be planted in concrete-filled post holes. So long as the deck surface is level, the project is a success.

The Final Dakar · Dec 28, 2012, 09:31 AM

Because we'll all be secretly judging him.

andi*pandi · Dec 28, 2012, 09:49 AM

I wonder how high off the sand the deck is. I could see levelling it if it's big enough to store things under (ie, lawnmower, yard supplies), also assuming you are putting some kind of lattice stuff up... and with bigger gravel underneath. I could also see levelling if you didn't want flooding out into the yard from diverted rainwater.

mattyb · Dec 28, 2012, 10:12 AM

My explanations weren't clear. Here is one of the terraces (approx 8.2 x 6.5 feet) :

8029/width/350/height/700[/IMG]

The overall thickness is less than 8 inches. (Plank + joist + concrete tile). The concretes tiles are approx 15 X 15 inches wide.

The upright post solution was considered overkill and would have involved more work than pouring a slab of concrete.

andi*pandi · Dec 28, 2012, 10:33 AM

ah, much different than I imagined. Most wooden decks I've seen have been suspended over the ground, I guess because the doors are not level to the ground.

That looks like a nice job, but if it's level with the stone (concrete?) why not put more of the same? or nicer brick/stones?

mattyb · Dec 29, 2012, 01:30 AM

Originally Posted by andi*pandi

That looks like a nice job, but if it's level with the stone (concrete?) why not put more of the same? or nicer brick/stones?

The concrete and tiles on the left of the picture are part of the house. If I wanted to do the same then I would have to ask for planning permission. The terraces that I made do not need planning permission, since they are not permanent structures.

Coldwater · Dec 29, 2012, 03:44 AM

Since there is limited information as to the method and steps you undertook I might be repeating your building process. If I were to build a similar structure, as you did i would remove the grass making sure you don't disturb the ground beneath, then lay out the fabric. I'd then set all the tiles to your predetermined height using either a laser level or at a minimum, a six foot level. Once they are all level in all directions, or if they need to be matched to the slope of your existing structure, and secured, add your aggregate or sand. I'm not sure the reason you are using sand as I would use crushed rock between medium and coarse. Fill the areas between the tiles almost to the top. Using a straight edge screed the sand or rock level using the tops of the tiles as a guide and fill in any areas that are low. This way you are not trying to move more material then you need to. I would then pre build the decks 2 x 4's under carriage to the size needed and place it on the tiles. Actually you can prebuild either part of or the whole deck if you have a level area and help to move it into place if you don't want to disturb the bed.

mattyb · Dec 29, 2012, 04:14 AM

Originally Posted by Coldwater

Since there is limited information as to the method and steps you undertook I might be repeating your building process. If I were to build a similar structure, as you did i would remove the grass making sure you don't disturb the ground beneath, then lay out the fabric. I'd then set all the tiles to your predetermined height using either a laser level or at a minimum, a six foot level. Once they are all level in all directions, or if they need to be matched to the slope of your existing structure, and secured, add your aggregate or sand. I'm not sure the reason you are using sand as I would use crushed rock between medium and coarse. Fill the areas between the tiles almost to the top. Using a straight edge screed the sand or rock level using the tops of the tiles as a guide and fill in any areas that are low. This way you are not trying to move more material then you need to. I would then pre build the decks 2 x 4's under carriage to the size needed and place it on the tiles. Actually you can prebuild either part of or the whole deck if you have a level area and help to move it into place if you don't want to disturb the bed.

I shall have to take photos of the next project so that my explanations are clearer. I have a feeling that the only difference is that you would place the concrete tiles directly onto the geo-textile fabric, whereas I used sand to get a level base for the concrete tiles.

This, I think, is the crux of my question. For a terrace or deck that doesn't go onto a concrete slab, but that will sit on 'earth', what is the best method for securing the joists.

Coldwater · Dec 29, 2012, 08:58 AM

Lay the deck frame on the tiles. Since there would not be a great deal of lateral stress I'd use something similar to Superstrut 2 Hole Angle Bracket lag bolted to 2x4, and using 1/4 in. by 2-1/4 in. Stud Anchors epoxied into cement tiles. Being that cement tiles have a tendency to crack while hammering in stud anchors, I'd drill the hole large enough that one needs only to lightly tap them into place. Blow out the holes with compressed air or vacuum out, make sure epoxy surrounds the anchor. Only expose enough of the stud anchor threads needed for nut because it will, or may interfere with attaching the lag to 2x4 as the holes are not offset.