the first brick courses

[happyhero]

Hi
Thinking of building my own garage and have a million questions. Here is my first one, hope its not a stupid one to ask.

You normally want your damp course to be 6" above the ground as I understand it (about 2 courses of bricks). When you lay foundations I see people often stop the foundations low and lay a couple of courses below ground level so that by the time you get to damp course level you have laid 4 courses. Why is this done? Why not just get your foundations to as close as possible to ground level and then just lay two courses? OR if it is to do with uneven ground levels just lay one course under ground level; surely foundations are much easier way to gain height than laying loads of brick courses under ground level, bending over and all

Please enlighten me.

 

[masona]

All depends what type of flooring it's going to be, example a floor screed will need 100mm hardcore or rejects finish off with pea shingles then a layer of pit sand to protect the dpm + 100 mm concrete on top finish off with 50mm sharp sand floor screed which you can't do in 2 courses of brickwork.

 

[brumylad]

I am no builder, but I have read that it is best practice to finish the top of the concrete foundation 150mm below ground level. I think this is to reduce the action of frost on the concrete.

These days house walls need to be wide because of new regulations regarding insulation. A lot of house builders are using thin concrete strip foundations and then foundation blocks on top, presumably its cheaper than masses of concrete.

But if you are building a garage the walls and hence the foundations will not need to be very wide, and you may as well go for trench fill concrete foundations.

 

[happyhero]

Cheers guys for the inputs. Masona, from what you say the thickness of the floor can be some 10 inches and then some, so are you saying you have to lay enough courses on the foundations to cover the thickness of the floor if you want it to be roughly level with ground level of the adjacent land?

Might be a silly question but could you not lay the floor in between the foundations with all its layers but where the foundations protrude into the internal area just lay the top screed over the properly layered floor and protruding foundations so that you end up with one level surface not letting you see afterwards which bits of floor are properly layered floor and which are just a layer of concrete over the foundations?

Also I have seen diagrams where it shows foundations and the floor being laid at the same time. What happens here, surely the floor ends up level with the outside land, but then surely there will be no bricks below ground level? Help?

I do realise what I am saying here and know it might be bad practice or totally the wrong way to do it, but I am trying to learn, so hopefully people will be patient with my crazy questions.

 

[masona]

Cheers guys for the inputs. Masona, from what you say the thickness of the floor can be some 10 inches and then some, so are you saying you have to lay enough courses on the foundations to cover the thickness of the floor if you want it to be roughly level with ground level of the adjacent land?

Yes but the dpm would have to meet up to the dpc which must be 150mm above ground level.

Might be a silly question but could you not lay the floor in between the foundations with all its layers but where the foundations protrude into the internal area just lay the top screed over the properly layered floor and protruding foundations so that you end up with one level surface not letting you see afterwards which bits of floor are properly layered floor and which are just a layer of concrete over the foundations?

The one I think you're talking about are many types of foundation such as rapid installation foundations for fast food like McDonalds to save costs & labour time. A lot depend on the ground conditions in difference area such as Canvey Island which have a 18" thickness raft footing right across the base acting as a floating footing including reinforcing which is expensive because of the marshes problem. The other one is a strip foundations which use less concrete.

 

[happyhero]

Hi Masona

Thanks for the reply. You're being very patient with my crazy questions.

Yes but the dpm would have to meet up to the dpc which must be 150mm above ground level.

So from this comment are you saying the garage floor would end up 150mm higher (plus the layers of screed) than the surrounding land? What would you do then if someone said they wanted it level so they could drive straight in with no slope? OR would you advise them to have the internal floor higher?

 

[masona]

Hi Masona

Thanks for the reply. You're being very patient with my crazy questions.

No problem

So from this comment are you saying the garage floor would end up 150mm higher (plus the layers of screed) than the surrounding land? What would you do then if someone said they wanted it level so they could drive straight in with no slope? OR would you advise them to have the internal floor higher?

To give you some idea a dpm & dpc in a house but a garage section doesn't have to be this way, see the 2nd picture for the same level without a slope as long the dpc is 150mm above ground level.

The most popular for garage base is this one.

 

[happyhero]

Cheers Masona for all that info.

In the middle picture am I right in assuming you build the walls and then the base?

Also I wanted to have my garage walls rendered, so I was thinking of using engineering bricks (I was told to use because they don't absorb moisture) up to the dpc and then some sort of block. Would this be the correct way to do it?

I want to cheat a bit with this garage, ie I was thinking of asking for permission to build a garage but although I would like to maintain access for a vehicle, I probably would use it more as a utility room and/or playroom for the kids, and therefore would like to try and achieve the same insulation properties as the house and would probably add a rad to my system in this area. When I had a attic extension done they used 9" Turbo blocks to bridge the cavity and give me the equivalent insulation of a cavity wall, (so I was told at the time) so I was thinking of using these for my garage. Would you say this is a good way to go or not, or would you say there was a better way?

Thanks in advance for any info.

 

[masona]

In the middle picture am I right in assuming you build the walls and then the base?

Yes, most builders build up to dpc level first then the concrete base

Also I wanted to have my garage walls rendered, so I was thinking of using engineering bricks (I was told to use because they don't absorb moisture) up to the dpc and then some sort of block. Would this be the correct way to do it?

Yes use engineer bricks up to dpc level then whatever type of bricks on top.

I want to cheat a bit with this garage, ie I was thinking of asking for permission to build a garage but although I would like to maintain access for a vehicle, I probably would use it more as a utility room and/or playroom for the kids, and therefore would like to try and achieve the same insulation properties as the house and would probably add a rad to my system in this area. When I had a attic extension done they used 9" Turbo blocks to bridge the cavity and give me the equivalent insulation of a cavity wall, (so I was told at the time) so I was thinking of using these for my garage. Would you say this is a good way to go or not, or would you say there was a better way?

As far I'm concern but check with BCO first, you can do what you like up to a point providing no one is sleeping overnight in the garage.

 

[happyhero]

Sorry if I'm being dumb here.

The second picture looks favourite and on this picture you see about 8 courses up to the dpc. All the base layers butt up against several of these courses which is fair enough.

I know the foundations are going to be wider or thicker than the wall but can the base layers butt up against some of the foundations and some of the layers, ie half and half, sounds messy I know but it would look right on top and would require less courses, or is this just bad practice.

Obviously if done as in picture 2 instead of the way I just mentioned it is a much neater job in theory but once finished you would not be able to tell the difference either way.

Can anyone put me straight on this bit please?

 

[masona]

Can you show us a drawing?

 

[happyhero]

Hi Masona

As I ask this, I feel myself wondering if I am asking a silly thing that no one would ever bother with.

Sometimes in my trade (electrician) people ask me what they think are quite valid questions, but are rather odd questions in fact, I then find it obvious why you would never do things that way for many reasons or even reasons I cannot think of at the time, so I try to put them on the right track. Maybe this is the case here only it is me asking these odd questions. Anyway you asked about a picture so I adapted your middle one to suit the question I asked.

Basically it may look a little messy but it would just mean more concrete foundations and less brick courses, say about 5 rows less so a lot quicker and easier I would think, and maybe cheaper but I am sure you will tell me why it would not be a good way to go. I am interested in what you think.

 

[TexMex]

HH Looking at your proposed plan, Imagine what you will have just before you lay your floor. Now look at that concrete foundation. It's protruding above the oversite. (the ground level inside the garage). What you need to ask yourself is, how will you achieve this, There are basically two possible methods.

1) Don't dig out the oversite until the concrete foundations have set. This will make your work much harder, as that concrete is going to get in the way when you are digging.

2) Dig out the oversite and then put up shuttering before you lay the concrete foundations. (Sounds like a lot of unnecessary work to me).

If you really want to have the concrete foundations up to ground level, why not go for something similar to masonas last picture. Effectively you will then just lay the base and foundations in one hit.

The main problem you may have is that the ground itself, is not generally very level. If you finish the foundations below ground level, you can use the first couple of courses to get your brickwork level, before it emerges from the ground. If you finish the concrete above ground level, you can use wooden shuttering to get a pretty good level surface to the foundations before you even start laying bricks. If you finish the concrete at exactly ground level you can do neither.

Even if your ground is level, it's s*ds law that it isn't going to be exactly level with the top of a course of bricks on the main building. (you are going to get the horizontal joints to line up with the main building aren't you?)

Bear in mind that any deviation of more than say 10mm from will cause you to start hacking bricks or having wavey brickwork. No problem if it's below ground level, but will look an eyesore if it's on display above the ground.

You pays your money and takes your choice. My prefered method is to have the brickwork start below ground level. Looks more professional (IMO) and gives you scope to get the brickwork level AND in step with the guage on the main building BEFORE it reaches ground level.

 

[happyhero]

Thanks TexMex, I think I have it now and sorry if I am asking dumb questions.

One thing I still need to ask then, not being a builder by trade, (its probably obvious to most) is, are you saying, to achieve masona's middle picture, that you work everything out and dig the foundations and floor area (oversite area if I understand your explanation correctly) at the same time to their respective depths?

If you say yes, then I understand, I had assumed you dig the floor after the walls are built, probably pretty silly I think.

 

[masona]

Have you started the footing yet? if so, can you post the picture so we can help you even you haven't started?

Agreed with Texmex regarding the last picture.