I’m about to build a raised deck on or bungalow which is on a sloping site so the deck will actually be around 1.8 metres above ground level.
I can’t tie it back to the building so it’s going to be supported on four columns which I plan to build either from facing bricks or possibly concrete
blocks which would have to be rendered.
I’ve got planning and have been told by building control that it doesn’t need building regs approval because it’s not structurally attached to the
bungalow. They also suggested the footings for the columns should be 600 x 600 x 225 deep which is somewhat shallower than I’d expected.
I would like to build the columns 1 ½ bricks by 1 ½ bricks which I’m confident will have enough compressive strength but I am actually concerned about
the ability to restrain any side loadings although I will tie the deck back to the bungalow wall even though it’s not strictly structural.
So do you think the columns will be OK or should I make them larger? (I really want them to be a slender as possible so as not to dominate the small
garden).
Should I fill the hollow central void of the column with concrete and re-bar? If so should the re-bar be fixed to re-bar set in the footings?
Will I need some form of cap stone on the top to spread the load of the timber beam which will sit on top and carry the flooring joists?
Any advice would be appreciated,
John.
You're over engineering things. Simple 4x4 timber struts (or 6x6 if you are of a nervous disposition ) concreted into holes with fastcrete are
adequate. Put diagonals between struts and it will be rigid.
Interim supports enable cheaper , shallower, joists to be used and all you need to do is foot them on a rough mortar mix with a slate on top to stop
rot.
Done this on 4 decks the largest of which is freestanding 20m x 10m with height tapering from 0.3m to 2m. been standing 12 years and as rigid and
strong as the day it was built. I drive my lawn tractor over it when I'm using the trailer to transport party stull to the deck and no
worries.
Cheers!
Have to say I agree with v8kid and would opt for timber columns to support the deck. Easy to do and quicker than messing about with brick/block columns. Use some diagonal timbers if you're still concerned over lateral stability.
My main structural concern was lateral stability but the reason for using brick columns was primarily for appearance.
We want the deck because we have fantastic sea views from the back of the bungalow but down at garden level you can't see anything. However the
garden is very small and the deck will certainly dominate it when you're at garden level so I want to keep the supporting structure as minimal
and visually pleasings as possible.
With bricks I hoped to have slim columns (though not as slim as timber posts I suppose) which would not require any diagonals for stability, would
match the walls of the bungalow and also not require any maintenance.
I can see timber would be easier to use and cheaper. Guess I'll have to have a think about it. I find it hard to visualize what it will look
like from below.
John.
Usual practice when building brick or stone gate pillars is to set a steel centre, square tube or I section, with the gate eyes welded to it, then
brick around it.
You could do similar, obviously you wont need the eyes, but the set steels would give you all the side stability you are looking for.
[Edited on 12/4/17 by r1_pete]
Steel is answer if you want skinny, with a bit of imagination you could make it look really good without having to bother clading it with anything.....
quote:
Originally posted by mcerd1
Steel is answer if you want skinny, with a bit of imagination you could make it look really good without having to bother clading it with anything.....
A brick pillar would have lots of compressive strength but would have very little lateral/bending strength unless reinforced with steel. ie - if you
simply built a 1 1/2 brick pillar, 6 feet high, you could easily push it over. It wouldn't take much lateral deck movement to crack one or more
of the mortar joints.
You could build it structurally with wood, or steel, and then build a brick facade round the verticals for appearance.
quote:
Originally posted by v8kid
quote:
Originally posted by mcerd1
Steel is answer if you want skinny, with a bit of imagination you could make it look really good without having to bother clading it with anything.....
Especially if you get it galvanised first
That is just lattice porn