How safe is it to fix a boiler of about 45Kg to a breeze block wall?
The manual states simply to fix it on a strong wall.
Breeze blocks are widely used for external wall (on the inner leave at
least), so I'm assuming it is safe.
Perhaps it is better to use suitable plugs...
Yes you can.
Keep in mind that the weight is predominantly in a downward direction.
You can use heavy duty long fixings suitable for the material.
I used polyester resin fixings for mine. This technique involves the
use of threaded studs of a diameter suitable for the holes in the
boiler mounting bracket, and of a length of (say) 100mm. Holes are
drilled into the wall 2mm oversize for the studs and cleaned out.
A special two part resin with one part containing mortar is injected
into the holes and the studs inserted. After a suitable time
(minutes to hours depending on resin and temperature, the bracket can
be fixed to the wall.
This method is ideal for heavy weights on breeze blocks because there
is not the risk of crumbling around the fixing.
Screwfix among others sell the materials
The ability to support loads is not the same as the ability to hold a small
fixing in place
If they are breeze block and not the soft Durox blocks you should be Ok
I normally cut wooden pads into breeze block walls and either skim with
plaster (or set the pads flush with the wall and tile over where I am tiling
I fit these pads with plugs and screws into the solid bits of the breeze
block rather than the cavity bits. I also use some gripfill as a belt and
braces approach but then I tend to over engineer most jobs
Having said that I have fixed Combi boilers direct to breeze block in
There was additional support via the big balanced flue vent and the support
plate at the bottom for the pipework so the boiler was not just supported on
the screw fixings
Thanks, I'll check it.
Meanwhile, I've forgotten a very important detail.
The wall at the moment is bare...no rendering, but I've planned to use
celotex insulation and plasterboard...I guess I'll have to use a
proper studding frame behind the boiler and then look for longer
screws (or these polyester fixings) to account for the thickness of
On the other hand, it may seem a bit wacky but what about fixing the
boiler straight to the bare wall and then later on fixing the
insulation and plasterboard all around the boiler? The cold bridge
shouldn't be an issue as the boiler is on when it's cold outside.
At the moment I haven't really made my final decision...I just prefer
to mount the boiler now and get the heating system going. The drywall
Tony says: "If they are breeze block and not the soft Durox blocks you
should be Ok"
Just to clearify. The blocks in question are areated...I can't think
of anything weaker than this stuff.
I've bought them from a local B&Q store....
Maybe I'll have to check my terminology better next time, but I think
my concerns were justified.
How heavy were the blocks - a 1 hand lift or 2 hand lift (breeze block) ?
Another approach is to fix a wooden plate ( ply) to the wall ( same size
as boiler) using several fixing and then fix boiler to plate.
This way you can make sure you get good a few good fixs for the plate (
the boiler fixing holes are bound to line up with mortar joints)
and fixing the boiler level will be easy.
I would be tempted to use a bit of 19mm MDF on some reduced depth studs
and plaster over that AND the board..use scrim tape between the
plasterbaord and tehe MDF to avoid cracking.
Ive done this a few times, and it makes for a very stable and easy to
use surface for screws and the like. Anytime I try to fix to
plasterboard and rip out the screws, I cut a bit out, notch the studs,
let in the MDF and plaster over...
So you will lose even MORE heat that way...
No. Dop teh drywall first and boiler up later.
Its a piece iof piss to knock up stud work with a bit pf MDF or ply on
it and the rest plasterboard..if money is available use ply throughout
instead of plasterboard actually. Skimming is the nastiest bit and thats
a LOT easier if there is no boiler in the way.
I always worry about aircrete blocks, but other folks on this group
tell me not to worry. But I am *still* not convinced ;-) I wanted to
use something else on my extension plans, but the walls would have had
to be much thicker thus losing interior space, and the BCO hates "non-
I will have to mount a boiler near the top of such a wall. I will
probably mount a large piece of 18mm ply (or thick cement board if
heat issues) with lots of long fixings and mount through this and into
the wall behind. Or mount an comprehensive angle-iron frame and fix
the boiler to that. This would give some lateral support to the wall.
It will be in some time of cupboard arrangement, so I may not
plasterboard the back of this.
It's all very well to say most of the weight is down, but when someone
slips and grabs the thing ...
1 hand lift for sure...and I'm not Hercules.
As I said I can't think any block or brick weaker than this
stuff....they were more expensive than high density blocks, apparently
the aerated ones are great for thermal insulation but not very
"trusty" are they? Or maybe it's just a psychologic issue.
Meanwhile I'll consider the wooden plate or other similar
solutions...just for a bit of piece of mind.
In article ,
They're probably concrete thermal blocks.
Breeze blocks were only used for a few years around 1930s.
Clinker blocks were used up to around 1970 and concrete thermal
blocks since then.
I have seen instructions on drilling concrete thermal blocks on
the manufacturers' websites. Contrary to what one might imagine,
you should drill them with HSS drill bits with no hammer action,
and not masonary drills. Aim to make a clean parallel-sided
cylindrical hole. When screwing into a plug, I lubricate the
screw thread to reduce the twisting force on the plug and
reduce the chance of it turning in the hole and wrecking the
On Fri, 30 Nov 2007 09:16:38 -0800 (PST) wrote :
That's likely to cause you big problems with pipe connections or case
screws buried in the wall.
Fixing to aerated blocks is not going to be a problem. Get the actual
fixing well into the block of course. If you need longer fixings to
take account of the insulation, my timber merchant sells long coach
screws intended for decking which would probably be ideal for this
Re some of the other posts re using a backing board of ply, fixing to
a combustible surface would probably fail a gas safety check.
On Nov 30, 6:27 pm, firstname.lastname@example.org (Andrew Gabriel)
Thanks Andrew, that's very valuable information.
There is more than just a block apparently...the blocks in question
are made by Celcon and the type is called Solar (not 100% sure).
Just checked their website...got to download some brochures.
Why the boiler manufacturers don't specify how to fix this stuff?
I was really opting for the wooden board...it seems safe enough...
Plasterboard is fire resistant though...maybe using a double layer
(only behind the boiler) for extra solidity should do the trick.
How are fixing all the celotex/plasterboard - just fixing direct to the
wall, or are you putting up studwork throughout? That's what I did
recently; I got a fixing template from my boiler manufacturer while
erecting it, so I could work out exactly where to position horizontal
noggins so that they would be in the right place to attach the boiler to
them. Measured and recorded the noggin height off the floor, then
celotexed, and boarded the whole wall and got it skimmed.
Then when the boiler installer came along, he found two parallel lines
drawn on the plaster along which he could screw the boiler frame. So
the boiler is supported on the studwork, not the wall behind.
Well, the way the drywall is going to be fixed is another issue which
needs to be sorted.
Your suggestion is to fix the studs to the wall, apply the celotex
between the studs, cover with plasterboard and skim.
The boiler should be fixed onto the studwork (bearing in mind of the
positioning of the screws.
Yet, ultimately, the loads are transmitted to the wall...or the studs
rest on the floor?
I guess I need to do some homework....
It semms ok though, the impact load to the aerated blocks is softened
by the studs.
The studs can be spread on a large surface of the wall = the load is
also distribuited on a larger area.
The only problem with studs is that the celotex isn't going to be
continous along the wall surface.
I was thinking of using aluminium studs...but these don't look very
Maybe I should use wooden studs in critical areas and aluminium ones
This at present is all guesswork.
Put that ply plate in..to make it easy..
I'd rest them on the floor: then the studs merely have to be attached to
not pull away from the wall.
You get the basic idea..you meed a horizontal beam bit at the floor base
to rest the studs ON and provide something to nail the skirting
to..thats your weight support member..
No big deal.
Al goes up fast, but its a hellofa cold bridge and expesnive.
Just get some 2x2 rough sawn or so and make up a floor beam and a
ceiling beam. and whack up studs between them using angled nails - one
from each side.
Add noggins and a ply plate inset into the studs for the boiler.
Fill between with celotex of 50mm and foil tape over the ruddy lot.
board up and skim.
That wasn't. Its more or less how my house is built, except I haven't
got the blocks,. so we used 4x2, 6x3 and 7x3 timbers for the walls, and
in some critical areas, a ply facing nailed over for extra strength,
Resin studs as described by Andy Hall will be fine.
- Drill a careful, smooth hole to the back of the block (but not through),
and blow the dust out with a length of tube, a vacuum cleaner etc
- Squeeze a length of waste resin onto newspaper until you can see the
colour change (the 2-part mixing isn't instant)
- Shove the nozzle in and fill about 50-75% of the hole, then gently push in
a length of threaded rod
- Twist the rod around, pull it in & out etc until the resin muck is well
spread, then leave it an hour or so.
- You'll be able to hang an anvil off 'em.
If you are dry lining, then you can make it simple for yourself by
placing noggings in the studwork at the right position to take the
boiler fixings. Then you can use normal screws to attach it without
needing to worry about getting a good fix.
Not a good idea... will make access to it a PITA, and you may find the
pipe terminations etc do not even clear the surface.
In article ,
And if you don't know exactly where that's going to be, blob-glue a bit
of tatty old ply or MDF to the back of the plasterboard - then you can
screw just about anywhere and the load's spread over a large area.
I've done that in several places in this house - like where I know in a
year or two there's going to be a shower but the details aren't