A bit of education required if possible required please.

[Big Jimbo]

I have some questions with reference to building a basement if any of you nice people can help. Rather than just leave it to an engineer, i would like to form some of my own ideas. Thanks in advance for any advice received.

1. When you install a floor / bottom in a basement, do you still need a load of insulation. If a basement is underground on 3 1/2 sides. Just a lightwell exposed. If that floor is say 4mt underground is the temperature not stable, and quite warm at that point ?

2. I believe that to comply with building regs you have to have Two methods of keeping water out ? Any idea what is normally done ? I was thinking about a french drain around the base to a sump with a pump which would take that water to a suitable soakaway ? I'm not sure what other methods might be used ?

3. I know that sometimes basements are constructed using formwork, and waterproof concrete.  Any ideas as to what other methods might be suitable ?

4. If a bathroom was to be fitted in a basement, i take it that a macerator pump would be required to take the waste up to ground level where it could be discharged into a normal 100mm soil pipe ?

5. Any directions to web sites, or you tubes, that might give me a better idea of methods available ?

6. Anything else you think i might need to consider ?

 

As always, thanks in advance for any help or advice offered.

[SteamyTea]

With regards to insulation (Q1),

Yes loads.

It is a brave assumption that the ground under a house will act as a thermal store. Even if it did, you have supplied the energy to heat it.

GSHPs work on the grounds that they extract the energy in the ground being the mean of the annual air temperature, so around 12⁰C for me. 

Always ask the question 'why is wine kept in a cellar'. It ain't because it is (expletive deleted)ing hot.

Edited June 13, 2022 by SteamyTea

[joe90]

18 minutes ago, SteamyTea said:

question 'why is wine kept in a cellar'.

To keep the temperature stable. ( I have built a wine cellar for a customer )

[joe90]

1 hour ago, Big Jimbo said:

If that floor is say 4mt underground is the temperature not stable,

Yes

1 hour ago, Big Jimbo said:

and quite warm at that point

Not necessarily but as said GSHP pull heat from the ground but at a very low level, at least there is no “wind wash” effect which can cool an above structure quite a lot.

[Thorfun]

1 hour ago, Big Jimbo said:

1. When you install a floor / bottom in a basement, do you still need a load of insulation. If a basement is underground on 3 1/2 sides. Just a lightwell exposed. If that floor is say 4mt underground is the temperature not stable, and quite warm at that point ?

yes, but you don't 'need' as much as at ground level. Have a read of this post for more details as to how depth underground effects U-values:

 

 

also there are other threads in the basement forum on this subject. e g.

 

 

1 hour ago, Big Jimbo said:

2. I believe that to comply with building regs you have to have Two methods of keeping water out ? Any idea what is normally done ? I was thinking about a french drain around the base to a sump with a pump which would take that water to a suitable soakaway ? I'm not sure what other methods might be used ?

 

2 methods for a habitable space, yes. we used waterproof concrete AND waterproof membrane. details in our blog:

 

we also have a land drain around the base of the basement going to a sump. very much belt and braces here.

 

1 hour ago, Big Jimbo said:

3. I know that sometimes basements are constructed using formwork, and waterproof concrete.  Any ideas as to what other methods might be suitable ?

 

we used formwork and poured reinforce concrete but you can also use ICF and @pocster used another form of blockwork that he DIY'd but can't remember the name of it.

 

1 hour ago, Big Jimbo said:

4. If a bathroom was to be fitted in a basement, i take it that a macerator pump would be required to take the waste up to ground level where it could be discharged into a normal 100mm soil pipe ?

 

yep, saniflo basically. or you could go to great expense and have a very deep waste pumping station externally.

 

1 hour ago, Big Jimbo said:

5. Any directions to web sites, or you tubes, that might give me a better idea of methods available ?

the basement sub-forum of this website! 😉

 

1 hour ago, Big Jimbo said:

6. Anything else you think i might need to consider ?

make provisions for utilities to come in to the basement if you're having a plant room down there.

[Pocster]

2 hours ago, Big Jimbo said:

I have some questions with reference to building a basement if any of you nice people can help. Rather than just leave it to an engineer, i would like to form some of my own ideas. Thanks in advance for any advice received.

1. When you install a floor / bottom in a basement, do you still need a load of insulation. If a basement is underground on 3 1/2 sides. Just a lightwell exposed. If that floor is say 4mt underground is the temperature not stable, and quite warm at that point ?

2. I believe that to comply with building regs you have to have Two methods of keeping water out ? Any idea what is normally done ? I was thinking about a french drain around the base to a sump with a pump which would take that water to a suitable soakaway ? I'm not sure what other methods might be used ?

3. I know that sometimes basements are constructed using formwork, and waterproof concrete.  Any ideas as to what other methods might be suitable ?

4. If a bathroom was to be fitted in a basement, i take it that a macerator pump would be required to take the waste up to ground level where it could be discharged into a normal 100mm soil pipe ?

5. Any directions to web sites, or you tubes, that might give me a better idea of methods available ?

6. Anything else you think i might need to consider ?

 

As always, thanks in advance for any help or advice offered.

Yo Jimbo

 

I'll chuck my pennies worth in.

 

When you install a floor / bottom in a basement, do you still need a load of insulation. If a basement is underground on 3 1/2 sides. Just a lightwell exposed. If that floor is say 4mt underground is the temperature not stable, and quite warm at that point ?

I installed EPS insulation under my basement slab. I also needed to make it a 'raft' form.

 

2. I believe that to comply with building regs you have to have Two methods of keeping water out ? Any idea what is normally done ? I was thinking about a french drain around the base to a sump with a pump which would take that water to a suitable soakaway ? I'm not sure what other methods might be used ?

My twat council said 3 forms to keep water out. I have french drain type affair at the base outside the basement ( this is expected to fail ). I had plastic sheeting lapped over all the external basement walls ( this is expected to fail ). The internal perimeter drain with floor and wall membrane is IMHO the only thing you need as this shouldn't ( can't? ) fail. So basically (expletive deleted) about doing the other 2 but don't spend too much time/money on them as they will fail.

 

3. I know that sometimes basements are constructed using formwork, and waterproof concrete.  Any ideas as to what other methods might be suitable ?

I used interlocking concrete blocks ( can find the brand name if you wish ). All dry fit. Nice and easy but lots of labour. I then tied thousands of steel rebar through the lot because I'm as 'ard as nails.

 

4. If a bathroom was to be fitted in a basement, i take it that a macerator pump would be required to take the waste up to ground level where it could be discharged into a normal 100mm soil pipe ?

Yep. But it all depends on where your soil pipe will be. I can't do this so I will need underground WC to macerate to a pumping station outside.

 

5. Any directions to web sites, or you tubes, that might give me a better idea of methods available ?

Yes. Just ask me. Because I'm (expletive deleted)ing brilliant.

 

6. Anything else you think i might need to consider ?

How much cash you got?

 

 

Edited June 13, 2022 by pocster

[Mr Punter]

1. When you install a floor / bottom in a basement, do you still need a load of insulation. If a basement is underground on 3 1/2 sides. Just a lightwell exposed. If that floor is say 4mt underground is the temperature not stable, and quite warm at that point ?

Yes you do, although not quite as much

2. I believe that to comply with building regs you have to have Two methods of keeping water out ? Any idea what is normally done ? I was thinking about a french drain around the base to a sump with a pump which would take that water to a suitable soakaway ? I'm not sure what other methods might be used ?

Often either waterproof concrete or external membrane and perimeter drain plus type C internal drained cavity.

3. I know that sometimes basements are constructed using formwork, and waterproof concrete.  Any ideas as to what other methods might be suitable ?

Concrete block

4. If a bathroom was to be fitted in a basement, i take it that a macerator pump would be required to take the waste up to ground level where it could be discharged into a normal 100mm soil pipe ?

Mini pump station is better and quieter as it does not need to blitz, only runs occasionally and has a decent bore discharge pipe..

5. Any directions to web sites, or you tubes, that might give me a better idea of methods available ?

6. Anything else you think i might need to consider ?

Ground investigation will have a large impact on the engineering. Also consider ventilation and fire escape.

[Pocster]

6 minutes ago, Mr Punter said:

6. Anything else you think i might need to consider ?

Go as big as you can underground because neighbor objections mean feck all to ‘size’ of dwelling they can’t see . Avoid having it that you must park on it - that’s a bit tricky 🙄

[SteamyTea]

2 hours ago, joe90 said:

4 hours ago, Big Jimbo said:

If that floor is say 4mt underground is the temperature not stable,

Yes

But if the temperature is no more than say 14⁰C in the summer, and closer to 8⁰C in the winter, all year round you are losing heat to the ground. Even if that heat is free, it is still leaking out.

Don't matter how stable the temperature is, if it is too cold, it is too cold. The Atlantic around here is stable, still not going in without a very thick wetsuit.

[Big Jimbo]

Yes i went in for planning permission for a basement that was the full size of the house above. with a decent sized lightwell to the rear. The reason for the basement was because i'm in Greenbelt and i knew that there was no way to go bigger on the house. Just got it through. I'll do some reading re the above advice. Thanks folks. I am pleased that i have managed to go from about 650 square ft to 3881 square ft + a double garage, and my posh shed. So about 4450 square ft in total. Ive had A and E permitted development rights removed.  A i can understand but E is a right cheek. I will try and post up my floorplans, so you can all pull them apart.

[Big Jimbo]

[Big Jimbo]

[Big Jimbo]

[Big Jimbo]

Big apols for being so tecno rubbish, hence the 3 posts. Thanks again for all the replies gang.

[Pocster]

7 minutes ago, Big Jimbo said:

I think one says ‘gym ‘ - it’s too small mate ! Make the gym bigger ! Also where does the arcade cabinet go ? , hot tub ? , sauna ? and  games room ?

[Big Jimbo]

10 minutes ago, pocster said:

I think one says ‘gym ‘ - it’s too small mate ! Make the gym bigger ! Also where does the arcade cabinet go ? , hot tub ? , sauna ? and  games room ?

You could always use the posh shed as a Gym. I might apply to get my Part E back. (There is no way it passed the six tests) just so i can build a pole dancing posh shed down the bottom of the garden. Obviously it would include a hot tub, sauna. arcade games etc (+ dancing girls) I would obviously invite the buildhub gang.

[Thorfun]

love it! and can't wait to see the progress once you get started. a few comments...

 

1. what is the area circled in red for? it's much more cost effective to build the square basement. adding that kink will add extra cost and I can't see a reason for it.

 

 

2. I would put the cinema seating in the middle and have the walkways at the sides. otherwise no one has the prime position of being central to the screen! Also, tiered seating would be amazing so consider your ceiling height when digging/building the basement and ensure you have room to allow it. it's exactly what I'm planning with our basement cinema if/when I ever get around to fitting it out. we have 3m high ceilings in the basement so plenty of room to allow tiered seating.

 

now I've seen the plans, another few things to consider for your plant room. If you're having MVHR (and I presume you are) and it's going in the plant room then you'll need a condensate drain unless you're having an enthalpy exchanger. 

 

our RWH has a 'brain' to it that flushes out the header tank if no use is detected, i.e. holiday mode, so that rainwater isn't sat in it for a prolonged period. As such I need to 'drain' from the controller which will be in the basement but as it's drained by gravity the controller needs to be above the RWH tank or drains! this is a problem for me and if I knew then what I know now I would've run a drain from the plant room to the sump in our sunken courtyard (same as your light well) so that any water that needed draining from the plant room could easily use gravity out to the sump. maybe you won't need it but thought I'd mention it now so you can consider it if you might need it. what's more frustrating is I did put ducting under the slab for electric cables from the plant room to the courtyard for powering the pump and lights, just never thought I'd need to drain anything....how wrong I was.

 

how big is your plant room and have you planned everything out? I thought ours was and it is just about ok but the MVHR ducting has taken up a lot more room than I anticipated. I have a separate plant room and comms/electric room to keep those items separated. I'm now a bit worried about the comms room as the Loxone cabinet for our HA system is quite big, and then when I try and fit a rack mount cabinet and the fuse box etc I think it might be a little tight. basically, don't underestimate how much room you'll need in the plant room.

 

think that's it from me for now as dinner is nearly ready. if I think of something else I'll let you know.

 

good luck! 🙂