Bolt down Metposts

[Newapprentice]

I'm about to build a deck on top of an exisitng concrete slab, I will use bolt down Metposts to hold a couple of posts in place.

The exisitng concrete slab is rough and uneven so I will smooth some concrete to form a smooth, level surface for the Metpost to sit on.

1/. I assume I should use 6 sharp sand, 1 cement?
2/. If I use quick drying cement can I drill through and fix the Metpost the same day?

Any help much appreciated.

 

[studips]

extra rapid setting cement sets very fast - but you'll likely crack it if you're using expansion fixings the same day as it'll still be fragile .

can you use a concrete in metpost? or have a look at screwfix products 66063 and 85498 (yes, i did look that up, my memory isn't that good mores the pity)

also this skim your using - how thick is it going to be? and 1:6 is a bit weak for me - more like 1:4 for a use like this.

 

[JohnD]

IMO you will get a better result by drilling the holes first, then placing the support with 12mm spacers, then packing the gap with mortar.

 

[Blagard]

I would knock off any especially high spots off the concrete so it is not quite so rough. Position your metpost, drill for the anchors. then use a washer or two as shims so that the four fixing points are sound and the metpost plumb. Then just bed the post base on a thin cement paste/slurry and tighten up your anchors. Basically just using the cement as a grout, and in such a thin layer shrinkage will not be an issue.

 

[Newapprentice]

Thanks for the advice - excellent.

4:1 slurry/grout. Building or sharp sand will be fine I'm sure?

 

[Deluks]

A deck built onto a concrete slab won't go anywhere. Doesn't need fixing down.

 

[studips]

i'd always fasten down - timber twists and flexes.

you can't easily fix them at a later date even if you can be bothered to, it's also a consideration of how tall your supporting posts are going to be