Porch Foundation (again, sorry)

[markblue777]

Ahh I have tried various types of bridging over pipes/ drain / ... Did not actually use lintol as thought it would come under what I thought is the proper term. Thanks though I'll have a look

 

[MMUK]

When it comes to lintelling over the pipes how does this actually happen, I know the basic of box round the pipe, fill with pea shingle then lintel over but what I dont get is how you then match the lintel height with the block work or am i missing something really obvious here? do you have a diagram or a resource that shows whats what perhaps?

Cheers
Mark

If the pipe is deep enough the lintol won't interfere with brick or blockwork, where there's an inspection chamber they are usually at least 18" below ground level. What I would normally do is dig my trench to about 12" below pipe level then shutter off around 8" from the pipe either side to about 4" above the top of the pipe. I concrete to this level and allow to cure. Once the concrete has gone off I remove the shuttering and fill the void with pea shingle, level to the concrete. Then I place lintols over the top with 12" bearing either side where possible and concrete the rest of the trench to finished height. I tend to finish my concrete no lower than two courses below ground level at the lowest point, it's unnecessary to blindly follow the main house trench height in cases where there are half a dozen or more courses below ground level.

 

[markblue777]

Ah thanks mmuk. I was wondering how a full trench fill is done. So by doing half the pour then pea shingle the lintol then the rest of the pour to finish height that is all and its done.

So the pea shingle protects the pipe from the rest of the concrete and the lintels spread the load from it

 

[RobinBHM]

The tricky part of your porch foundation is how close it is to the inspection chamber. I guess if it quite close, It will probably become exposed as you dig down your trench. Unfortunately I dont know how its best to resolve, but hopefully somebody on here will. For building works diy.com forum have some helpful people.

 

[Lons]

The tricky part of your porch foundation is how close it is to the inspection chamber. I guess if it quite close, It will probably become exposed as you dig down your trench. Unfortunately I dont know how its best to resolve, but hopefully somebody on here will. For building works diy.com forum have some helpful people.

Doesn't matter if the chamber is close to the founds as long as the founds are deep enough not to affect it. Just backfill the void with pea gravel and it's fine.

 

[DennisCA]

Can't you just remove the soil and replace with gravel with draining properties, or is that overengineering? I'm casting a slab that's 3x3 meters infront of my garage, I have gravel as a foundation and I am putting 5cm of insulation under the plate and out 60 cm around the plate to prevent frost heaving.

I also have french drains going around the garage with 4 underground wells, one for each corner, the lowest situated well has a drain pipe as well. So the slab will be going over one of these pipes, I don 't see that as an issue.

The form I'm building:
https://farm4.staticflickr.com/3905/186 ... 33bd_b.jpg

There will also be plastic foil against the foundation of the garage, to keep it as a separate slab that doesn't move with the garage foundation.

I'm not really following the discussion that well, having a hard time picturing what you're after, first post seems to talk about a wooden porch, but then the discussions seems to be talking about slabs, which is why I showed what I've done.

EDIT:

If you just want some foundations to build a timber porch on, then this would work, this is a picture of the foundation for my house (what you see as the ground here becomes underground later, it's all filled in):
http://farm8.staticflickr.com/7412/9947 ... b8f5_c.jpg

See those plinths on the right, those are the foundations for my porch. They sit on, what else, gravel. Mixed cheap gravel for the majority of the ground, then just under the foundations there's coarser, better draining gravel, in my case also insulation but you don't need that in the UK I think. Gravel and drainage is the key to building here in Finland, get water away so the ground doesn't, freeze, move and heave.

Here's the blueprint too (left), but in the wrong language:
http://i.imgur.com/9i3bWFk.jpg

I don't think it would be much work to dig out for some concrete plinths like these, and put down some coarse gravel as a foundation, then also fill in with gravel around the plinth. Rebar is neccessary of course.



Also a lot of people here nowadays make timber porches with these steel foundations that are just giant screws they screw into the gorund.

 

[markblue777]

Hey all

Yeah the chamber will be exposed when I dig the trench. About 1/4 of it i would imagine.

I assumed as you have said lons that I dig to below so the weight is pushed under it and then box the chamber and pipe off, lay the strip. Then pea shingle and lintel over the pipe.

After I take the block work up to dpc I just back fill with soil? Could I back fill with some pea shingle to help with draining as well?

Cheers
Mark

 

[Lons]

Hey all

Yeah the chamber will be exposed when I dig the trench. About 1/4 of it i would imagine.

I assumed as you have said lons that I dig to below so the weight is pushed under it and then box the chamber and pipe off, lay the strip. Then pea shingle and lintel over the pipe.

After I take the block work up to dpc I just back fill with soil? Could I back fill with some pea shingle to help with draining as well?

Cheers
Mark

Yes and yes!
On the outside of the found you can back fill with what you like, inside is different of course. gravel is always a good idea imo for additional drainage protection.

Mark. Without wanting to be blunt, I think you're in danger of an information overload which might just end up confusing you. I fully appreciate that if you don't know, then you don't but you've had replies and sound advice from several professionals and TBH I could have built it in the time the thread has been running. :lol:
As I said previously, It ain't rocket science so don't get sucked in to over complicating what should be a pretty straightforward job.

cheers
Bob

 

[markblue777]

Yeah I understand it all from what has been said now so will crack on with it after I have finished the other bits in the house that need doing. Should be able to start in a couple of weeks (need to wait for the house purchase to go through before I can do anything as well)

Thanks for the help everyone and I will make sure I do a WIP project. It will be a good way to document it as well.

Cheers
Mark

 

[Lons]

Yeah I understand it all from what has been said now so will crack on with it after I have finished the other bits in the house that need doing. Should be able to start in a couple of weeks (need to wait for the house purchase to go through before I can do anything as well)

Thanks for the help everyone and I will make sure I do a WIP project. It will be a good way to document it as well.

Cheers
Mark

Look forward to seeing that Mark, I'm sure you'll make a very good job of it.