Building an Extension (Garage and Block Selection)

[Andrew Welham]

Dear all

After reading the news groups archives and the building regulations for the past few days. I have made some (but slow) progress in the design of my extension. What I have so far is:

My house (1960s) semi detached is 6445mm wide and 7130mm in depth (excluding the porch). I have a side entrance with is 2360mm with at it narrowest point (including the brick wall which I am responsible for

450mm wide). I have a private (I think council not back from Christmas yet) drain running parallel to the back of my house, with the edge of the man hole cover being 2680mm from the back of my house (and ending 3200mm from the back of the house).

I have an old garage in the back garden, which starts 4200mm from the back of the house. This will eventually be demolished, since it is made on a solid slab, and I don?t want to loose any more garden this will turn in the patio after the rebuild has been completed. Therefore my back wall of the extension must be between 3200mm & 4500mm away from the house. That?s the background out of the way, but I thought it might be helpful.

The garage will be built in the side entrance and I need it to be as wide as possible.

Can I assume the 450mm wide brick wall that I am responsible for is on my land and therefore when I remove this wall my foundations can take up the space where this wall once sat ?

I am planning for the garage on using 100mm (building regs say 90mm Min) concrete block in a single leaf wall with from end bonded at least

190mm(this will also form one side of the door way. The other end will be bonded to a two leaf wall which will form also contain dual doors (30 minute fireproof) for access to the extension living area. The regulations also say there must be piers at a maximum of 3000mm apart since the garage will be 7133mm long I am planning on having two piers at approximately 2377mm intervals. The doors between the garage and the main living area will be will have a step not less that 100mm high, and any pipes entering the garage from the existing house greater than 40mm will be fire proofed.

Dose this sound ok to every one? Have I missed anything?

I am still looking into the roof. I defiantly want a flat roof to stay in keeping with the neighbours. I assume I can have a cold roof for this un-insulated garage? Made up I guess of marine ply and multiply layers of felt (3 I think).

The roof joists. One end is fixed to the wall I will build out of concrete block. The other end I assume is fixed to the house by joist hangers? One answer I can?t seem to find is,

What do I do about the bit of the garage between the top of the door frame and the roof? Does this have to be block, and if so what holds it up or can it be made of wood and fastened in the same way as the joists?

The garage will be built first then the extension, but while I am thinking about blocks The last question in this post, should I and can I use the 100mm concrete blocks for the inside and outside walls of the main extension which will be going across the back of the house and garage. I am planning on rendering the garage and extension to ensure they are in keeping with the neighbourhood.

Many thanks

Andrew

[Owain]

"Andrew Welham" wrote | The garage will be built in the side entrance and I need it to | be as wide as possible.

1. It might be very useful or essential to keep external access available to the back garden - you don't say whether this will be available on the other side of the house - rather than having to take the lawn mower etc through the garage and back extension (also for fire brigade to get a ladder up to back bedrooms). You migth also have to leave a gap between the wall and the boundary to allow for foundation width, guttering, or maintenance.

1. If there is any possibility that you could have a first floor extension above the garage at a later date, get the foundations sized and the ground floor walls built to satisfy building regs for a two-storey building now. It will add very little to the cost now but make things much easier in the future. By 'any possibility' I mean whether the position of walls, roof, windows, makes any sense for the first floor to be extended out to the side, rather than whether the planners would pass it now. Planning policies can change. If there is such a possibility, consider that a new bedroom above the garage might want an en-suite, so put in the ug drain now in preparation for a soil stack.

Owain

[Set Square]

I'm trying to get my head round this lot - but here are a couple of initial comments/queries.

Are you sure that the brick wall on the remote side of your side entrance is

450mm (18") thick? What is on the other side? You may be responsible for it, but I'm not sure that that necessarily means that the boundary is on the far side of it. I have a feeling that foundations (which will necessarily extend out further than the outer edge of your new garage wall) need to be on your land - so it's important to bottom out these issues.

It seems to me - from the dimensions you have stated, that the internal width of your garage - particularly where narrowed by the piers - may be insufficient to get a car in or - at any rate - to open a car door once it is in. This all needs calculating very carefully.

Over the garage door, you could use a wooden frame covered by ship-lap or similar. Otherwise, you'd need a lintel with blocks above it.

I don't quite understand about the manhole. Is it going to be *inside* the extension? Is it storm or foul (or combined)? Incidentally, getting an answer as to whether it is public or private may not be straight-forward - because many of the records seem to have got lost - in my area at least - in the local government reorganisations in the 70's or whenever! [You'll probably find that if you want to build over it, it's public - but if you want it unblocking, it's private! ]

Your living accommodation extension will need to satisfy all the latest building regs with respect to thermal efficiency - which requires a high standard of thermal insulation. I can't quote any U values off the top of my head - but I imagine that you will be required to use insulating blocks for the inner layer - and maybe to dry line on the inside of that.

[Andrew Welham]

I will keep access to the back garden via the doors at the front of the garage, then through the extension (utility room part). Double doors all the way. This will allow me to bring large items in via a different route, as well as a separate fire exit, As for lawn mowers they will be kept in the new shed then its built :) that one comes next.

Its a good idea, but I don?t think I will need to do that, and the chances of planning permission for anyone on our area to have that done is minimal. But a good idea any way.

[Andrew Welham]

3rd time to resend this item (sorry if the failed attempts appear too).

Set Square wrote: > In an earlier contribution to this discussion, > Andrew Welham wrote: >

sorry my mistake 45mm i.e. 1 brick wide

Yes I must keep the foundations on my side of the boundary. I guess the council will be able to tell me where the wall is actually placed. I was thinking if the wall is on my land then that gives me an extra 45mm(got it right this time ) to put my foundations on.

I have no plans to put a car in the garage. You?re quite right it?s too narrow. I intend to use it for more of a store room basically used for every thing a garage is used for except storing a car.

*inside* the > extension? Is it storm or foul (or combined)?

It?s a combined drain. I was intending to put the sealable covers on, and have a removable panel in the new floor so in the emergency when I need to access the drains, I can simple remove the floorboards and access the drains after removing the sealed cover.

Incidentally, getting an > answer as to whether it is public or private may not be straight-forward - > because many of the records seem to have got lost - in my area at least - in > the local government reorganisations in the 70's or whenever! [You'll > probably find that if you want to build over it, it's public - but if you > want it unblocking, it's private! ]

I did see it on the computers at the council when I originally checked a year ago. The project got shelved shortly after that, and is now returning to life again >

That part I have not looked in to as yet, but i think from a brief look your right. Just looking for further confirmation , as the regs dont seems to be exact on the issuse.

While I?m on the subject of building regs, why are some of the PDF documents scans of paper docs, makes it a complete pain, can't do a search with acrobat.

[David Hemmings]

Remember that their are different rquirements if there is living space above, e.g. jiffy hangers if used must be of the heavy duty variety. So whilst you would get away with normal jiffys for single storey, you wouldn;t for living space above. This point is obvioulsy moot if building the joists into the wall or using a wallplate.

[Andrew Welham]

what is recommended for single storey garages, and also single storey living dwellings

[Hugo Nebula]

On Fri, 02 Jan 2004 15:29:28 +0000, a particular chimpanzee named Andrew Welham randomly hit the keyboard and produced:

Councils get Xmas day, Boxing Day and New Year's Day off.

The inspection chamber or manhole will be bigger than the cover. You need to lift the cover and check the internal dimensions, then add

102mm or 225mm for the walls of the chamber and at least 50mm clearance between the extension walls and the chamber. Bear in mind that the chamber will have a footing to it as well, and your wall footings should be separate from these. If the chamber is staying, then the closest point of the extension will probably need to be at least 600mm away from the centre line of the drain (assuming it's not a Public Sewer and can be built over).

Sod's law says that the original builders covered the drain in about

400-500mm surround of concrete, so be prepared for a lot of hard work in breaking this out with the end result that you crack the pipe anyway and have to replace it.

I presume you're talking about a cavity wall. If so, then yes, provided that you insulate the cavity. The wall between the garage and the extension is classed as an external wall and the amount of insulation needed will be virtually the same as a fully exposed wall.

[Owain]

"Andrew Welham" wrote | > It seems to me - from the dimensions you have stated, that the | > internal width of your garage - particularly where narrowed by | > the piers - may be insufficient to get a car in or - at any | > rate - to open a car door once it is in. This all needs | > calculating very carefully. | I have no plans to put a car in the garage. You?re quite right it?s | too narrow. I intend to use it for more of a store room basically | used for every thing a garage is used for except storing a car.

Check whether that is acceptable to the planners; even if you have a full car's length drive in front of the garage they may require 1.5 x or 2 x off-street parking spaces per household.

| While I?m on the subject of building regs, why are some of the PDF | documents scans of paper docs, makes it a complete pain, can't do a | search with acrobat.

because John Prescott can't touch-type.

Owain

[Hugo Nebula]

On Fri, 02 Jan 2004 20:08:42 +0000, a particular chimpanzee named Andrew Welham randomly hit the keyboard and produced:

It's nothing to do with the Council (Building Control or Planning), so make sure you know exactly where your boundary is.

They only started putting the Approved Documents on as proper PDF files from (IIRC) 2000. ADs which have not been amended since are just scans, which makes them huge and next to useless.

[Set Square]

I'm still confused! What sort of brick is 45mm wide? Do you mean 4.5" (~115mm)?

Have you considered the effect on the resale value of the house of having a garage which isn't a garage?

I wouldn't fancy that inside *my* house! Is there any possibilty of re-routing the drain away from the extended property? [Also see Hugo's comments on necessary clearances]. There was a long thread about sealed inspection chambers inside houses a month or two ago - it might make interesting reading!

I think that the regs are written in terms of the overall U values to be achieved, rather than telling you what materials to use. But in practice there are only certain combinations of materials/construction methods which will meet the regs. I'm sure that your local BCO will provide some helpful advice if asked.

[Andrew Welham]

This should not be a problem as I can currently fit 2 cars in my front driveway, and another 1 or 2 where the garage will be. Plus I?m going to remodel the front garden to make it easier to get the cars in and out. I need to do this any way, but it has to be done before I start to build (once I get planning permission).

: )

[Andrew Welham]

Third Time lucky yes your currect, when i was measuring i was working in cm, just read the wrong part of the tape sorry :(.....

To be honest no, as I have no plans to move, when this house was purchased, I planned to raise a family here and not to resell the property. Plus how may people actually park a car in a garage these days, most people I know park on the drive way, I will have room for cars plus a garden once this is done. Still a very valid point and one to be considered

I did reconsider this, however the drains run along the back of all the houses in my part of the street. So the entire drain could not e rerouted, however the man hole cover could be(did not think of that) , I will have a think and also read the articles your talking about.

Thanks I am planning on talking to the BCO, but would like to have as much info as I can first, to save looking like a complete idiot :) I have also spoken to a few builders merchants and will pick up some booklets with their recommendation of the blocks to use so I can meet the over all U values.

>

[Andrew Welham]

They still were not answering their phones on the day after new years day.

Thanks looks like I have some unexpected work ahead of me. I will also read the thread on internal drains I heard was running earlier.