Building regs implications on planning / external house design

[Moonshine]

I am developing a site (detached house) and am half thinking about putting the planning drawings together myself, or at least having a good think about the house layouts / siting.

 

Can anyone provide any implications of building regs which may have a impact on the house design and layout at planning stage?

 

My initial thoughts are as below for key issues, but i am sure there are other things i haven't considered;

 

• Approved Document A - Provide enough spacing for floor construction for structural requirements, as could have an impact on final ridge height, i am assuming 200mm for complete internal floors, 400mm for structural / concrete floor between garage and habitable space above inc floors and thermal insulation.
• Approved Document L1A - provided enough spacing for constructions with thermal insulation, 400mm for structural / concrete floor between garage and habitable space above, 300mm for external walls (cavity), 300mm for pitch roof or a ceiling level.
• Approved Document M - the site is on a slope so may need to provide an access ramp to front door level? corridor / door widths for indicative internal layouts for wheel chair user, upon further reading of this assuming planning permission doesn't stipulate it, it would like be a Cat 1 dwelling (visitable dwelling) which would need the following access;
  • uniform steps of rise of 75-150mm, min going of 280mm, with tread nosing.
  • Min clear width of 900mm, with hand rail to one side.
  • requires a landing every 1.8m of rise, and top and bottom, with a min length of 900mm.

 

Any thing else that needs considering?

Edited October 2, 2018 by mike m

[the_r_sole]

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Edited September 26, 2019 by the_r_sole

[Moonshine]

5 minutes ago, the_r_sole said:

imo, you can't really just consider regs in isolation, they all have an impact on the look of a house - you'd be better to start designing then look at the issues the design has with regs in mind

 

Interesting point but i disagree, such as approved document E isn't applicable as its a detached property, also there must be some others that have no impact at the planning stage, e.g Part P, - Electrical Safety.

 

Its probably for the best that i read them and see what impacts they have, but i am sure a lot of the requirement won't effect what gets submitted at planning, though happy to be proved wrong. 

[the_r_sole]

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Edited September 26, 2019 by the_r_sole

[Mr Punter]

B and K

[Moonshine]

Just now, the_r_sole said:

 

Parts of E apply to internal constructions in dwellings - but obviously you know best so I'll step away - good luck with it

 

Thanks, I can't believe I forgot about that requirement!! R_w 40 dB for internal walls and floors. This can be achieved pretty straight forwardly and doesn't have an significant implication on planning drawings, with an allowance of 200mm for internal floors, and 100mm for internal walls.

[Temp]

300mm for external walls (cavity)

 

 Is it going to be brick and block or timber frame? Is that enough for a brick and block house? How much do you need to allow for the void in the  cavity these days?

[Moonshine]

2 minutes ago, Mr Punter said:

B and K

 

Cheers, i will have a read through

[Moonshine]

7 minutes ago, Temp said:

 Is it going to be brick and block or timber frame? Is that enough for a brick and block house? How much do you need to allow for the void in the  cavity these days?

 

Current thinking is brick and block, most of all the new builds i have seen recently are two leaves of 100mm block with 100mm cavity, typically with 50mm PIR board in the cavity, though with 100mm aerated block on the inner leaf.

Edited October 2, 2018 by mike m

[Temp]

1 hour ago, mike m said:

Approved Document M - the site is on a slope so may need to provide an access ramp to front door level?

 

Definitely. However the ramp doesn't always have to be very obvious. It's possible to hide it in a long path that winds around steps or similar. Sometimes the BCO wants a level and suitably finished access from the pavement to the front door. Other times he just wants it from the car parking space to the front door. 

 

If the house will be multi level indoors then the WC must be on same level as the door with the ramp. If your WC will be narrow with door and WC pan on opposite sides watch out for the need to get a wheelchair past the basin to the pan.  I had to hunt down a narrow basin as we got it slightly wrong.

[Jeremy Harris]

There can be some impact from Part M on odd things, I found.  I ended up moving our house slightly to the West on the plot to allow enough room for the access ramp to the rear door and the requirement to "enable a wheelchair user to manoeuvre into the dwelling".  I was advised that this meant I had to provide a flat area outside the back door (which is at the top of the access ramp) to allow a wheelchair user to turn through 90 degrees and enter the house, together with the normal flush threshold.

 

You don't have to use the front door for wheelchair user access, BTW, any entrance level door can be used to meet the Part M requirement.

[Temp]

1 minute ago, mike m said:

Current thinking is brick and block, most of all the new builds i have seen recently are two leaves of 100mm block with 100mm cavity, typically with 50mm PIR board in the cavity, though with 100mm aerated block on the inner leaf.

 

I would put more than 50mm of PIR in the cavity if building again . At least 75mm, ideally 100mm.

 

I also have concerns that builders don't always butt together the sheets of insulation very well. If I could figure out how to do it I'd prefer two layers with staggered joints or some sort of filled cavity.

[Temp]

4 minutes ago, JSHarris said:

I was advised that this meant I had to provide a flat area outside the back door (which is at the top of the access ramp) to allow a wheelchair user to turn through 90 degrees and enter the house

 

That can work well. For example if you have steps down off the flat area as well as the ramp, the steps have to be 90cm wide anyway.

 

I appreciate we have a lot more space than most but this is what we were allowed. Ignore the wood, I have been fixing loose slabs. The bit on the left is (was going to be) reinforced grass but never got around to laying grass on it.

 

[Temp]

41 minutes ago, mike m said:

approved document E isn't applicable as its a detached property

 

Perhaps things have changed but it was to mine. I was one of the first houses after part E was introduced to have a concrete first floor. The first BCO I had wanted me to provide Robust Design Detail drawings for a concrete floor with UFH to show it met E2b. They didn't exist at the time as apparently nobody had done the necessary tests.   Eventually I found a beam and block company that had done their own test and provided me with a copy of their certificate. I was able to convince the BCO that adding UFH on top could only improve things. 

 

They also gave me grief over the sound and fire rating of my downlights.

[Moonshine]

42 minutes ago, Temp said:

 

I would put more than 50mm of PIR in the cavity if building again . At least 75mm, ideally 100mm.

 

I also have concerns that builders don't always butt together the sheets of insulation very well. If I could figure out how to do it I'd prefer two layers with staggered joints or some sort of filled cavity.

 

good point and I will increase the min cavity i think, you can get tongue and grooved PIR boards to negate this issue

[Moonshine]

1 hour ago, Temp said:

Definitely. However the ramp doesn't always have to be very obvious. It's possible to hide it in a long path that winds around steps or similar. Sometimes the BCO wants a level and suitably finished access from the pavement to the front door. Other times he just wants it from the car parking space to the front door. 

 

Having looked at the issue a bit more, i don't know if i need a ramp. My local council highlights that not all dwellings need to be entirely wheelchair accessible and requires that 5% of new houses on a development need to be wheelchair accessible. Now what i am not sure of is how they will look an just a single house development.

 

Also in regard Approved Document M, the 2016 amendments, introduced 3 categories, and planning portal indicates that a ramp, Categories 2 and 3 apply only where required by planning permission.

 

https://www.planningportal.co.uk/info/200135/approved_documents/80/part_m_-_access_to_and_use_of_buildings

 

So i think that i will design based on it being a Cat 1 building, but think how i could incorporate a ramp.

 

Edit, i have just seen that the steepest ramp i could have is 1:12 in max 5 m lengths, meaning i would need 30m of sloped ramp in 6 lengths, plus the turns!

Edited October 2, 2018 by mike m
clarification

[Hecateh]

1 hour ago, mike m said:

 

Having looked at the issue a bit more, i don't know if i need a ramp. My local council highlights that not all dwellings need to be entirely wheelchair accessible and requires that 5% of new houses on a development need to be wheelchair accessible. Now what i am not sure of is how they will look an just a single house development.

 

I think it depends on your building control officer.  Mine has said it's not important when it's a single house built for yourself.  He's very pragmatic about a lot of things.  He won't compromise on safety or insulation but beyond that he's happy to be flexible.  (He's from a private company, not local authority)

[Oz07]

5 hours ago, Temp said:

 

That can work well. For example if you have steps down off the flat area as well as the ramp, the steps have to be 90cm wide anyway.

 

I appreciate we have a lot more space than most but this is what we were allowed. Ignore the wood, I have been fixing loose slabs. The bit on the left is (was going to be) reinforced grass but never got around to laying grass on it.

 

nice looking drum there

[Temp]

 

6 hours ago, mike m said:

Having looked at the issue a bit more, i don't know if i need a ramp. My local council highlights that not all dwellings need to be entirely wheelchair accessible and requires that 5% of new houses on a development need to be wheelchair accessible. Now what i am not sure of is how they will look an just a single house development.

 

Pretty sure you need a level entry and more...

 

My reading of the amended Part M is that  the three categories are progressively more suitable for disabled people but all have level entry requirements and more..

 

M4(1) Category 1: Visitable dwellings (least suitable)

M4(2) Category 2: Accessible and adaptable dwellings

M4(3) Category 3: Wheelchair user dwellings (most suitable)

 

Planners can decide how many of each they need in their area and can impose planning conditions requiring some to be M4(2) or M4(3).

 

My reading is that Cat 1 represents the situation before the 2015/16 amendments. (eg Even Cat 1 Dwellings need level access and WC on entry level etc.) 

 

Only M4(3) are required to be "entirely wheelchair accessible". I assume these need to have bedrooms on the entry level as well. 

 

This is consistent with what your council has said... "not all dwellings need to be entirely wheelchair accessible"  = Not all need to be Cat 3.

 

Note that Part M requires "level access". Many people interpret that to mean a ramp because floor levels are traditionally set above ground level.  I haven't checked but I don't think there is anything stopping you putting the floor level at ground level. This would eliminate any need for a ramp and also give you a level transition  from living room to patio. There would be design issues with the DPC and preventing rainwater running under doors but I don't think these are unsurmountable problems. I'd like to see the NHBC issue a construction detail drawing showing how this can be done, if they haven't already.

 

Edit: Indeed I had forgotten about basements! You can have the floor level meters below ground level if you wanted. The regs only require the DPC to be 150mm above ground level on the outer leaf. They don't require the floor to be 150mm above ground level.

Edited October 2, 2018 by Temp

[Moonshine]

49 minutes ago, Temp said:

Planners can decide how many of each they need in their area and can impose planning conditions requiring some to be M4(2) or M4(3).

 

My reading is that Cat 1 represents the situation before the 2015/16 amendments. (eg Even Cat 1 Dwellings need level access and WC on entry level etc.) 

 

Only M4(3) are required to be "entirely wheelchair accessible". I assume these need to have bedrooms on the entry level as well. 

 

This is consistent with what your council has said... "not all dwellings need to be entirely wheelchair accessible"  = Not all need to be Cat 3.

 

Thanks for your thoughts, and i agree that M4(2) or M4(3) planning condition dependent, but M4(2) or M4(3) are 'optional requirements', see

 

https://assets.publishing.service.gov.uk/government/uploads/system/uploads/attachment_data/file/540330/BR_PDF_AD_M1_2015_with_2016_amendments_V3.pdf.

 

Quote

requirements M4(2) and M4(3) are 'optional requirements' as defined in the Building Regulations. An optional requirement only applies where a condition that one or more dwellings should meet the relevant optional requirement is imposed on new development as part of the process of granting planning permission. Where no condition is imposed, dwellings only need to meet requirements of M4(1)

 

So, if the council does not set it as a planning condition then it just has to be M4(1), having looked a house locally that was granted outline planning permission early this year, there is no planning condition stating it has to be M4(2) or M4(3), so i take that as being M4(1) as the norm, though it i am ever granted permission without said condition i will be getting written confirmation that the intent is M4(1) so there would be no issue with BC.

Edited October 2, 2018 by mike m