Celcon/Plasmor/other

[Adrianlondon]

Hi all

I'm looking at which blocks I should be buying for my extension. It will be a single story extension which will be the usual 2.4m high.

I would like to use bricks with the potential of building above it in years to come. I doubt I will ever actually build on top of it but you never know what will happen in the future.

This is for my own house so I don't want to use sub standard products.

I've been told of different makes like Celcon and Plasmor. One builder I spoke to recommended Plasmor. Another Celcon.

HELP ME!!!!

The room being built will be used for a kitchen/diner and living room.

I've been told to use 7.3N bricks. Is this also correct?





Adrian

 

[tony1851]

If you use Celcon, or one of the other lightweight blocks, you will be fine for building a second storey at a later stage.
You will also get a better insulation value (for a given width of cavity insulation) using lightweight block.
The dense, 7N blocks have a higher load-bearing capacity, but you loose on insulation value.
And the higher strength is not really a material consideration in domestic extensions.

 

[Adrianlondon]

If you use Celcon, or one of the other lightweight blocks, you will be fine for building a second storey at a later stage.
You will also get a better insulation value (for a given width of cavity insulation) using lightweight block.
The dense, 7N blocks have a higher load-bearing capacity, but you loose on insulation value.
And the higher strength is not really a material consideration in domestic extensions.

Thank you for the advise. I'd rather save on the insulation value. As it is doubtful I will ever build on top of it.

Meanwhile, now I've been convinced to use lightweight blocks, can anyone advise me which make. One bricklayer recommends using Plasmor blocks as they are better when it comes to putting plasterboard on them (apparently).

 

[ban-all-sheds]

If you use Celcon, or one of the other lightweight blocks, you will be fine for building a second storey at a later stage.
You will also get a better insulation value (for a given width of cavity insulation) using lightweight block.
The dense, 7N blocks have a higher load-bearing capacity, but you loose on insulation value.
And the higher strength is not really a material consideration in domestic extensions.

OOI, what sort of difference does it make to the footings to allow for that possibility?

 

[theoldun]

To comply your target U value is 0.28 W/m2K
There are numerous ways to achieve this target and the one we prefer for various reasons is,
Brick. Solid fill with 100mm, DriTherm 34 super, either Plasmor Aglite or Plasmoor Fibolite, Dot, Dab and Skim
We prefer Aglite as they are a more dense block, still a one hand lift, more open textured for keying to and cut well.
Would not touch Celcom with barge pole.
Regards oldun

 

[Adrianlondon]

If you use Celcon, or one of the other lightweight blocks, you will be fine for building a second storey at a later stage.
You will also get a better insulation value (for a given width of cavity insulation) using lightweight block.
The dense, 7N blocks have a higher load-bearing capacity, but you loose on insulation value.
And the higher strength is not really a material consideration in domestic extensions.

OOI, what sort of difference does it make to the footings to allow for that possibility?

As far as I'm aware, as I'm digging 1.5m down and filling to approximately 1.2m I don't think I'd have a problem regarding the footings. A lot of councils only ask you to dig 1m or maybe 1.2 so the fact that I'm going down to 1.5 probably makes little difference.

I'm no expert (as it is shown through my posts!!) but I would imagine that if you were considering building an extension and you were told to dig 1m down, if you were thinking about a second story in years to come, I'd actually dig 1.5m so there are no arguments with the council.

 

[tony1851]

For a given soil bearing capacity, the depth of the foundation is usually immaterial, whether it is a one-, two- or three storey house; it's the width of the footing that is important. That depends on the bearing strength of the ground, but in the vast majority of cases, 600 wide is usually OK.

 

[Adrianlondon]

For a given soil bearing capacity, the depth of the foundation is usually immaterial, whether it is a one-, two- or three storey house; it's the width of the footing that is important. That depends on the bearing strength of the ground, but in the vast majority of cases, 600 wide is usually OK.

You see.........what do I know!!!

A much more knowledgeable person can give a much better answer than me!!!

On the bright side, I've also learned something new. Every day's a school day.

 

[theoldun]

]

I'm no expert (as it is shown through my posts!!) but I would imagine that if you .

Normally we would not answer your posts, but in this instance. as you have shown honesty, we will do so.
Unless you know the area in which you are working, or have not dug a 2m deep trial hole and possibly had an Attererberg soil test carried out, then you will have no idea of the ground conditions you will encounter.
Providing you know what you are talking about you can drive a coach and horses through section 2E and table 10 of ADA.
The reason that 9 out of 10 BCI ask for a metre dig by 600mm wide is to cover their backside.
There are three depths to cover the volume change potential, low. medium and high, with high being the metre dig. Unless you are within the zone of influence of trees or shrubs or very poor load bearing ground, then a metre dig should suffice for a two storey building.
With regard width of foundation. A traditional two storey detached house, including imposed load and snow load weighs in at approx 30 to 40 KN per metre run. Now refer to Table 10 and you will see why we dig all our foundsations 450mm wide, thus saving our selves £700 per plot.
At 450mm wide and a 300mm cavity wall you must set out and dig very accurately.
You may get some smart ar*ed BCI tell you that you need 150mm projection of foundation each side of the cavity wall, but this only applies to strip foundations and not trench fill..
Hope this has been helpful to you.
Regards oldun

 

[ban-all-sheds]

I'm no expert (as it is shown through my posts!!) but I would imagine that if you .

No I didn't.

Normally we would not answer your posts, but in this instance. as you have shown honesty, we will do so.

Jolly good of you, but in this instance you are not answering a post of mine.

The reason that 9 out of 10 BCI ask for a metre dig by 600mm wide is to cover their backside.
There are three depths to cover the volume change potential, low. medium and high, with high being the metre dig. Unless you are within the zone of influence of trees or shrubs or very poor load bearing ground, then a metre dig should suffice for a two storey building.
With regard width of foundation. A traditional two storey detached house, including imposed load and snow load weighs in at approx 30 to 40 KN per metre run. Now refer to Table 10 and you will see why we dig all our foundsations 450mm wide, thus saving our selves £700 per plot.
At 450mm wide and a 300mm cavity wall you must set out and dig very accurately.
You may get some smart ar*ed BCI tell you that you need 150mm projection of foundation each side of the cavity wall, but this only applies to strip foundations and not trench fill..
Hope this has been helpful to you.
Regards oldun

It's been helpful to me, as I've got a situation where I'm extremely interested in making my foundations as narrow as possible.

 

[theoldun]

Should write that he is a waste of space

 

[ban-all-sheds]

I wrote this:

OOI, what sort of difference does it make to the footings to allow for that possibility?

and said that I found your post helpful.


So would you explain why this was called for?

Should write that he is a waste of space