Ask The Trades - Print Page

Ask The Trades
https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl DIY Forum >> Building Questions >> Brick pillar/plynth https://www.askthetrades.co.uk/cgi-bin/yabb/YaBB.pl?num=1237838338 Message started by CWatters on Mar 23^rd, 2009, 7:58pm

Title: Brick pillar/plynth
Post by CWatters on Mar 23^rd, 2009, 7:58pm

I'm building some small brick pillars/plinths using just four bricks per course. The foundations are concrete pads which have their top surface about two courses below ground level. Planning to use engineering bricks for the below ground courses but the ones I have are a perforated type. In addition there would be a hole down the middle of the pillar about 4 or 5 inches square.

Potentially water could accumulate in these voids. Is there a danger that it could freeze and crack the pillar or some bricks?

Should I fill the voids with concrete or would concrete also expand and contract at a different rate to the bricks?

Title: Re: Brick pillar/plynth
Post by JerryD on Mar 23^rd, 2009, 9:53pm

It's usual to fill these holes as you build using the bricklaying mortar. These bricks are Class B and are totally frostproof so the filled holes and filled centre core of the pier will have no ill effects from frost.

If you want to fill the centre core of the pier with concrete rather than mortar that's fine, just a bit more effort as you need concrete as well as mortar. The core can be filled after the pier mortar has 'gone off' and this avoids the possibility of the pier being disturbed by the core filling.

If these pillars are tall or for gates then a steel reinforcement should be set into the footing pad to rise throught the central core and then you should only fill the core with concrete rather than mortar.

Title: Re: Brick pillar/plynth
Post by CWatters on Mar 24^th, 2009, 8:36am

Thanks for that. Will go with the mortar fill. I usually find I've mixed a bit too much anyway.

They will have some oak posts on top so are really a plinth rather than a pillar. No gates or anything that might impose a bending/side load.