Timber frame porch build

[Hills_90]

Hi all,

 

New here but have come across a lot of the forum posts through google searches, so I thought id attempt to pick your collective brains.

 

I am planning to put a porch on the front of my house, the idea is to timber frame the build onto a concrete footing. I have put concrete bases in for a couple of sheds before but this is a bit more involved so want to check some details. I may end up getting a builder to look at this but id like to do it myself just to say I did that if i'm honest.

 

As it stands the area looks like this;

 

   

 

The porch will almost fill in under the original canopy roof, in reality it will protrude a little further than the front door but that is un important its the footings that are my main concern.

 

The image below is what i had been planning, excuse the crude paint design work.

 

 

Hope this make sense! Does this look sufficient for damp proofing and insulation? Also the overall depth is something that i am struggling to find any 'Concrete' information on (pardon the pun) I have found suggestions based on my soil type from anywhere between 500mm and 1000mm, the floor level actually be 250mm higher than the external ground level anyway to be the same as the original internal floor height.

 

Sorry if this is a very rookie question and thank you in advance for any information/suggestions 

 

Josh

[Hills_90]

I have also just realised i may have posted in the wrong section if i have apologies feel free to move the post into the foundation section

Edited September 3, 2020 by Hills_90

[Russell griffiths]

Busy this morning, but that needs a re, think

you have loads of insulation in the floor but have missed any cold bridges from the footings up to the sole plate, will be large condensation issue, and massive cold bridge at skirting board level. 

 

Have a read back on some previous posts, regarding garden rooms and foundation, loads been discussed recently, you would be better of with an insulated slab. 

[Hills_90]

Thanks for the reply Russell, will look into the cold bridge issue. Are you suggesting that there may be too much insulation across the flooring?

 

[Russell griffiths]

15 hours ago, Hills_90 said:

Thanks for the reply Russell, will look into the cold bridge issue. Are you suggesting that there may be too much insulation across the flooring?

 

You can never have too much insulation, but it becomes pointless if cold can get in somewhere else. 

[Mr Punter]

I would not worry about cold bridging for this as it looks like it will only be a lean-to.  You do not need to mess around with the blockwork inner leaf.  Just build the brickwork, fill with well compacted type1 to required level.  DPM, insulation, concrete.  Omit the screed.  You should be able to get the concrete OK with such a small area and the brick to work to.

[Hills_90]

Hi Mr Punter, so you are suggesting, cold bridging aside, the above would be fine without the inner block. Using just the brick to retain the compacted type 1 and presumably only the footing for the brick as the concrete infill between courses would no longer be required either? It needs to pass a building regs check as the front door will be moved into the porch from the existing position.

 

Russell, struggling to find anything that makes sense to me regarding the sole plate and cold bridging could you elaborate a little more please? Would you suggest the use of something like this between the DPC and the sole plate? Or is there a simpler solution I’m not aware of

 

thanks

 

Edited September 5, 2020 by Hills_90

[Russell griffiths]

Have a look at this, but ignore the block n beam and substitute that for a slab of concrete on the ground. 

Theres many ways to skin a cat. 

[Hills_90]

So if i am understanding you both then something along these lines would be more appropriate? With the maroon being the Marmox insulating block

Edited September 5, 2020 by Hills_90

[Russell griffiths]

Sort of but the levels need a bit of adjusting 

if you draw a diagonal line from out to in there is a cold path through the brick into the concrete floor. 

You also don’t need the screed, just finish the concrete better and no screed needed. 

[Hills_90]

So lose the top red brick, get the insulating block level with the floor insulation so that there is no masonry “contact” from outside to in?

[Russell griffiths]

so by altering the floor height you can bring the insulation up, at the moment you only have the perimeter strip between cold brick and your floor, that strip is normally only 25mm thick. 

[Hills_90]

That makes perfect sense, Thank you