Reasonable size of gap for services in blockwork.

[epsilonGreedy]

I plan to finish laying my garage block footing trench blocks today and I need to incorporate a gap for the entry of services. These services are:

 

1. Mains water.
2. Mains electric in a conduit.
3. Telephone & ethernet cat-6 cables.
4. Central vacumn system pipe (provision just in case I fit one with the main unit in the garage).

 

The gap will be in the first course above the poured concrete to ensure the services are at regulation depth and the course above will be in dense 19kg blocks which I hope can be used as lintels to bridge over the service gap.

 

How wide should this gap be? My hunch is 100mm or up to 130mm.

 

I have already done the course bonding maths for the second course to ensure the bridging dense blocks will have a 100mm support either side of the gap.

[PeterW]

Anything that is above 100mm from memory requires a lintel 

 

Water has to come in a minimum 750mm below ground and in a 63mm blue duct or 110mm soil pipe to give you the radius needed to get vertical inside the property. 

 

Telephone needs standard BT duct, electric needs black duct min 450mm below ground - DNO can advise what they require. 

[Declan52]

I put all my services in via a long 110mm 90 degree bend. Only one that didn't need brought into the house was electric as it comes up the cavity to sit inside the meter box which has to be accessible from the outside in NI.

I used 65mm concrete lintels. If you leave a gap 1 block long,450mm, you build 2 bricks 2 high either side of the hole. The lintel then bridges the opening and will sit flush with the next course. This will give you an opening that will be able to house 2 110mm bends.

Will look like this. If you need more that 2 bends then it's easy to make it wider like the pic.

[epsilonGreedy]

28 minutes ago, PeterW said:

Anything that is above 100mm from memory requires a lintel 

 

 

Ok a lintel it is. Basic cast concrete or with reinforcement rods?

 

This part of the garage structure is single story and with a ground baring concrete floor slab.

 

30 minutes ago, PeterW said:

Water has to come in a minimum 750mm below ground and in a 63mm blue duct or 110mm soil pipe to give you the radius needed to get vertical inside the property. 

 

 

Is the water supply ducting specific to routing the water pipe through the building foundation? I ask because I thought the pipe could be laid in p-gravel in the main external trench. Anyhow maybe I should duct the supply from house to garage because we are only talking 3 meters between external walls.

[epsilonGreedy]

30 minutes ago, Declan52 said:

I put all my services in via a long 110mm 90 degree bend. Only one that didn't need brought into the house was electric as it comes up the cavity to sit inside the meter box which has to be accessible from the outside in NI.

 

 

Your photo convinces me to go for a full block gap because this would allow a more direct run between house and garage, just a 45 degree bend in this case.

 

The electric meter box will be in the house but even so I suppose routing the mains cable up the empty cavity to the garage spur consumer unit results in a more tidy job and no need to armour the cable up the inside of the garage wall.

[ProDave]

The bricky doing my foundations put a lintel over every opening. To me it looked silly putting a lntel over a bot of 63mm duct for the tv aerial cables but he said that is what BC will expect.

[Temp]

I know this is for your garage but I recall reading somewhere there was going to be an Approved Document for service entry points. The idea is so new houses can have fibre broadband later. Did that come to anything?