help... not enough planning and too much doing.

[dunnes2002]

Good evening, I started on my oven build today and quickly (not quick enough) realise that my concrete base wasn't really big enough. I'm now slightly worried that the paving slabs and supports will fail under all the weight.

My current thoughts on a remedy are to either
-Use some brackets to sure up the overhang
-lay another concrete slab on top to make stronger
-use smaller slabs
-jack it all in and start again
This is my first attempt at bricklaying etc so go easy on the image you are about to see.

Does anyone have any advice?

I planned to use thermolite blocks on top of the concrete slabs similar to this build mikesbrickoven.blogspot.co.uk/2013/03/my-oven-build.html?m=1

Attachments:

[cannyfradock]

Hello Dunnes....welcome to the forum.

You're not on your own.....this is a common problem. Many people build a base without calculating the footprint of the oven.

As paving slabs aren't re-enforced with re-bar I agree that the slabs are cantilevering too much to give "piece of mind" when putting so much weight on the weaker edges. You have 2 options in my view to overcome this with the supporting walls as they are. Remove the slabs then...

1...cast a concrete slab with overhanging box shuttering to the required size. If re-bar is used in the slab you can cantilever the edges by at least 6" all round...or

2....use pre-cast lintels to overhang your walls. As long as each thermolite block touches 3 lintels similar to this...



...it will work. this method may leave you short of the length of your slab, so you may have to build another wall in front of your supporting walls.....it's only bricks and mortar....it's your build...anything and everything is possible with bricks and mortar.

These are just my thoughts. Please don't sue me if it all goes t*ts up.

Terry

[faz]

I agree that the paving slabs won't be strong enough to use with an overhang. I think Terry is right - I would take them off and cast a reinforced concrete slab on top of your columns. I think you can get away with a cantilever bigger than 6" but you need to make sure that there is rebar and/or mesh in there. You can only do this bit of the build once so it is worth doing it well!!

[dunnes2002]

thank you both for your suggestions

Jun 3, 2013 5:29:58 GMT faz said:

...... You can only do this bit of the build once so it is worth doing it well!!

i think you have hit the nail on the head with that comment. I want the oven to be a bit of a focal point and be proud of it. So i think the only option is to knock it down and start again. I think you always would have done things a bit different if you had to do it again and ill be able to do this by getting hold of a cement mixer to start...... and buildind the footprint the same size as the slabs!!!

lets hope the weather keeps up because this is going to take a little longer than expected!!

[faz]

I don't think that you can take the slabs off but leave the supports. A reinforced concrete slab will allow you to cantilever and increase the size of your slab. If you take a look at my build you can see the entire entry of my oven is built on a cantilevered extension to the slab. Plenty of rebar and about 4" thick concrete seems to have done the trick!!

ukwoodfiredovenforum.proboards.com/index.cgi?action=display&board=pompeiiovens&thread=291&page=2#2911

[dunnes2002]

right im back on it.... original effort has been dismantled.. much more fun than building!!!

Ok now im after a little bit of advice, the new base will be 1.2m sq and about 10cm deep. Do i need to use some rebar or at worst some chicken wire to add some strength?

Im uming and arring at the minute and think rebar might be a bit over the top. The soil underneath is mainly clay and paving slabs have been laid on it previously, not much weight on it though.

Any advice would be great as i don't wont to start over again. Cement mixer arrives tomorrow, job starts on Sat... getting excited all over again!!!

[bookemdanno]

If you can get some A142 reinforcing mesh from your nearest Merch, then drop some in the footing. It helps to tie all the concrete together and spread the load of the oven. Chickenwire isn't really up to the job here.

If you want to cast a slab onto the block/brickwork then the reinforcing mesh is the way to go too. You can also use Reinforced Concrete Lintels, again from your Merch, they're cheap and will take the load and then you can lay your big paving slabs over them. With the slab or lintel method, just make sure that they sit fully on top of the supporting blocks or bricks.

[dunnes2002]

thanks for the advice bookem, just added some mesh to my order and bought a grinder to cut it to size. Grinder will also come in usefull for the bricks.

All sorted for a busy weekend

[spinal]

Grinder + Bricks = Dust (lots of it)

Make sure you also have some protection, bits fly off at stupid speeds! Eye, ear and dust protection is a must if cutting bricks with a grinder
M.

[dunnes2002]

thanks for the advice, safety gear already purchased.

Dont think ill get as far as cutting the bricks this weekend... just the rebar!

[spinal]

Also, I would suggest changing the disc when cutting bricks - the black discs wear out in no time on bricks/concrete.

I used a diamond/steel disc, similar to this one to smooth off the edges of my bricks (I cut with a chop saw with a diamond blade):


I reckon something like this may work too:
www.ebay.co.uk/itm/9-Inch-230mm-Diamond-Cutting-Disc-Hard-Brick-Masonry-Concrete-Tiles-Stone-/360600379818?pt=UK_Home_Garden_PowerTools_SM&hash=item53f57521aa

It's quite hard to get an accurate cut with a grinder (or, I found it hard with my limited skills :p0
M.