Timber frame extension

[Jake2021]

Hi guys ,

Just a little guidance if you could… I’m going to be building a 3x2 rear extension on the back of our kitchen , I know I’m going to need building refs but will
Be under PD.

I’ve been thinking about the footings and wondered if it would be feasible to dig a 1metre deep pad stone and lay one concrete lintel/rsj from the pad stone to one wall on the house which this end will be laid on the rafter of the house and another from the pad stone in the other direction to the rafter on the other wall creating a L shape?

In theory it would be like a floating lintel and build to dpc in brick then timber frame ontop
Of this? Blue are the lintels/rsj and the black the padstone… I thought since it’s less weight then blocks it may be a feasible option?
Thanks
Jake

 

[^woody^]

Yes, are describing a standard pad and beam foundation, which is used for certain building types. It would need to be properly designed and proven by calculation to be acceptable to building control.

But the issue is why would you want to do this? It will involve more risk from movement and longevity/maintenance.

It's really a choice where other options are not available or viable, not a first choice.

Weight of a timber frame or a masonry extension is irrelevant in terms of what foundation and depth is required - which will be the same for either.

 

[Jake2021]

Thanks for your reply woody, I was going to trench fill it and standard masonry however as we are mid terrace, we have loads of neighbouring drains running through the location which will be a nightmare to move and very costly, it’s also got a high water lever and clay soil and finally it’s surrounded by huge trees which we are unable to move as in neighbour gardens.


We have to got through a few gardens to get out of our back way due to being a terraced so least hassle would be welcomed by the neighbours and would save me some massive back breaking work.

Thanks
Jake

 

[stevie888]

Your suggestion has merit but will need proper design: if you have trees then the depth may well be need to be > 1m deep. PCC litels would be your best bet as steels would need to be encased in concrete.

 

[^woody^]

Find out the size and depth of the drains and whether they are your responsibility (lateral drains) or the water company's (public drain/ sewer) or even the neighbours lateral drains with an easement over your land. You will need the water company's permission if public drains/sewers, so check if you will get it.

You may have good reason for using non traditional foundations, but get a professional opinion based on a site visit, and weigh up the risks, benefits and costs. Mini piles may be an option. A structural engineer is the only one who can give accurate advice, not any old plan drawer who you may use for general extension design.

 

[Jake2021]

Cheers woody

 

[Jake2021]

Appreciate everyone's help thanks all