Laying some blocks for a dwarf conservatory wall

[realtek]

Hi,

I am building a dwarf wall for a conservatory using foundation blocks + theremal blocks.

I have laid the first course of foundation blocks along the small side and since everything has dried, I checked again this morning and it seems about 3 blocks are not completely level a few mm.

I just wondered if it was a major issue or nothing to worry about as there will be one more course of foundation blocks on top which I can get level with no problems I know the first course will not be plumb with the second course and worst case but due to the size of the foundation blocks (300mm) etc and because they will be below ground if it was an issue structurally?

Because its the small side (3.5 m) and will only have about a 600mm wall (+200mm) for below DPC whether it was an issue.

From my point of view I don't it being a major issue as some foundations are not level (although mine were), so I am just treating these as almost another level of it and can correct any deviations on the next course.

Thanks

 

[^woody^]

It's not engineering. Don't worry about it.

 

[realtek]

Thanks Woody,

Do you have any tips on preventing the aircrete blocks from absorbing so much water so quickly?

I ended up making the mix a lot wetter which did make it easier to lay them but it doesn't take long before it starts drying.

I'm using Plasticiser added into the mix.

Mind you, it was very hot over the past few days which I know needs the mix wetter than usual. I heard about wetting blocks from someone first but I have since heard its not recommended so otherwise I will have to carry on as I am.

Cheers

 

[^woody^]

For what you are doing, soak them with a hose. Doing the blocks you will use on a course right before you are about to lay them might be better for you if you are not too fast.

A wetter mix does not help, but plasticiser does

 

[realtek]

Thanks woody, I will give it a go!

 

[realtek]

Hi Woody, foundation blocks are all in. Everything is still square.

Due to issues on the day of when we poured the foundations, we left it 75mm below the original target and decided to make up using bricks.

My question is, would you put engineering bricks as the next course on top of the foundation blocks or use blocks first and then bricks? (the outer skin will be aircrete as well as inside and it will all be rendered). (I need to get up to 300mm to the DPC), so one block and a brick.

No cavity infill is required as I am just above ground with the foundation blocks.

I would like to have some air vents, I have not read up if these should be below DPC or above yet, if below DPC then I am thinking of putting blocks in first otherwise the air vents will be too low of what will be covered outside as there will be a patio eventually which will come up to above the foundation blocks.

Would you also recommend those plastic weep holes? along the first course on top of the foundation blocks? If so, will they be effective if there is no infill to 'sloap' the water towards the outer leaf?

Thanks

 

[^woody^]

I would use engineers below DPC and 2-3 course below ground. But IIRC, you are using blocks in this location and rendering below DPC too? In which case you probably don't want a band of bricks of different material, as this will likely show through the render as a damp or darker band.

Air bricks either vent the internal via a liner, or vent under floor via telescopic 'periscope' sleeves. you can put them wherever is practical.

Weep holes are only required where a tray or cavity fill will cause water to build up at that course level. For a conservatory wall, rendered and with cavity fill, the potential for moisture in the cavity is low, so weep holes probably not really needed.

 

[realtek]

Thank you Woody.

Yes I will have to render below the DPC and above, I assume the renderer will use some type of beeding along the DPC.

I was a bit concerned about rendering the Aircrete as I read up that it can crack the rendering over time but if a good scratch coat is used then it should be ok. Not sure your thoughts on it but dense blocks are quite heavy and me laying bricks would take a much longer time really, I was looking for speed.

When I said Air bricks I meant for ventilation in the cavity, I think the periscope type are for underfloor venting, correct? I will be having a solid floor.

I take your point on the bricks showing!, I may decide to cut blocks lengthwise to avoid that but I will have a think.