Small extension help

[sarah barrows]

Hi, I'm doing a small flat roof extension (18 sqm) to give me a new kitchen area and I need a bit of advice on a couple of things. Its a smaller house with a dormer extension for the first floor.

 

I have good recommended subcontractors for each discipline, but I'm trying to clarify exactly what bits each of them do and when they should do it.

 

The new extension will intersect with the pitched roof, so I'd love to have a list of work in chronological order so that I can manage it properly. I could also do with a section through (just a hand drawn would be ok) so that the guys know what to do.

 

I'm also a bit confused at which timber bits the normal chippy will do and which timber bits the roofer will do.

 

• brickwork
• cut through existing pitched roof to receive new flat roof.
• do the structural timber work.
• roof timber.
• roofing.
• brickwork infills.
• roofing finishing (flashing to brickwork infills).

 

And how do I do this so that any rain doesn't get into the existing area during the cutting through work??

 

This would probably an hour or 2's work for someone with experience. Is there any way that I can pay someone to do this (free would be better but I don't mind paying!!)? Please let me know if this bit is not appropriate for this forum.

 

Hope you can help!!

 

[Redoctober]

Hi Sarah and welcome to the forum - You are in the right place so no worries on that front. I'm sure others with more experience than I in this field will pop along in due course but in the meantime, have a read of the attached link - it might assist.

https://www.homebuilding.co.uk/extension-planner/

 

PW.

[Ferdinand]

Welcome.

[MikeSharp01]

Welcome - Sequence and interfaces between the trades becomes everything in this sort of project - being clear of everybody's scope and knitting the scopes together is vital. Covering up is not difficult if needed but probably the knock through can be done once the extension is actually part built and perhaps largely watertight. Have you a drawing that might help us understand what you are doing?

 

Otherwise a typical sequence might be (Not exhaustive):

 

Get design including specifications for materials / finishes etc.

Get planning permission.

Get building control on board.

Ground works - including any soil pipes, electric / gas / comms ducts etc. (Usually the ground worker)

Foundation formation - fitting any insulation, laying DPM and pouring the concrete of a particular specification to a tolerance in the ground works. (Usually the ground worker)

Walls including damp proof coursing, insulation, window apertures and airtightness. (of whatever construction - sounds like timber frame in your case). (Chippy)

Roof timbers, sheathing - wooden surface, Vapour Control Layer if required, air tightness and link work to existing roof. (Chippy) {Rainwater goods probably needed here as well to take water from roof}

Cut into existing roof and cover up. (General builder type work but chippy might to it)

Roof covering including VCL if not in chippy scope, EG membrain, and refitting / making good any tiles from sloping roof to meet new flat portion. (Roofer - they usually want a flat, boarded / sheathed, surface to work from and connect roof to rainwater goods)

Brick infills, required damp proof courses, associated insulation and structural connections(Bricklayer)

Cut through existing building including fitting structural steel if needed. EG Lintel / RSJ (General builder)

Fit windows and maintain / continue airtightness (Window company or general builder)

Complete outer surfaces EG render or whatever. (General builder or specialist depending on finishes}

Internal fit out EG second fix etc, without damage to airtightness. (General builder / Electrician / Plumber)

Plastering / Drylinning (Plasterer / dry liner)

Kitchen fit (Kitchen fitter)

Decorating (Decorator, significant other - if persuadable or yourself!)

Kitchen warming party.

 

Each one will need a clear scope and check that there are no gaps and minimal overlaps (no point in paying twice) between the scopes.

 

Hope this helps.

 

Edited April 24, 2017 by MikeSharp01
Added plastering

[sarah barrows]

hi Mike thanks very much - very very helpful.

 

hope you don't mind just a couple more questions...

1. it's brick and block construction only 2.5m height - so I assume bricklayer will go from groundworks engineering course and do brick/block/insulation. a) what do I need to do for air tightness and b) re apertures, do the windows need any timber framing or just leave openings? or does the brickwork finish into the aperture?

     2. who will need scaffolding and at what stages do I use it? scaffolders have quoted a 'single lift' what does that mean?

 

     3. would a decent bricky, chippy and roofer do their work by discussions on site and therefore not need drawings? I can do hand drawn elevations to show doors, windows and general dimensions but I'm not confident to do a section through !!

 

With this info I'm really confident to manage everyone and I'm really looking forward to starting !!

 

[sarah barrows]

Thanks Redoctober for the planner. I'm using this.

[MikeSharp01]

20 hours ago, sarah barrows said:

1. its brick and block construction only 2.5m height - so I assume bricklayer will go from groundworks engineering course and do brick/block/insulation. a) what do I need to do for air tigntness and b) re apertures, do the windows need any timber framing or just leave openings? or does the brickwork finish into the aperture?

     2. who will need scaffolding and at what stages do I use it? scaffolders have quoted a 'single lift' what does that mean?

 

     3. would a decent bricky, chippy and roofer do their work by discussions on site and therefore not need drawings? I can do hand drawn elevations to show doors, windows and general dimensions but I'm not confident to do a section through !!

 

Hi Sarah.

 

1.  Yes Bricklayer will do all of that, a. depends on building control requirement for an extension and just how air tight the rest of the house is. Essentially you need to make sure that you don't reduce the overall airtightness of the whole house and preferably improve it to make the insulation in the extension work that bit harder. If you are plastering the inside then this will usually do much of it but making sure you get a good seal around the windows and any doors will also be useful, if you have any pipes / services running through the walls then these need to be sealed well. Ensuring good air tightness needs to be in all the sub contractors' contracts as it is no good if the plasterer does a great job and then the plumber just punches a great hole through and does not make good. b) you will need some sort of detail around the windows in brick / block construction this is usually done with a cavity closer - such as here. The window fitters will then seal the window to the specification you set for them. There are loads of standard details for this out there, such as here.
2. Singles lift means just one surface at the level of / suitable for the roof by the sounds of it. The bricklayer probably won't need it if only 2.5m high but the chippy, fitting the roof structure and cutting into the exiting build probably will and the roofer also. Work with the scaffolders to make sure that their scaffolding does not interfere with other trades' work such as the roof structure chippy, down pipes (rainwater), any service penetrations and windows and doors as you will get those trades moving the scaffolding and that is a big no no and you don't want to keep paying for the scaffolders to come back and move it out of the way of the window fitters.
3. Although they will probably work from verbal instructions you will find yourself answering loads of questions and paying for changes that could have been avoided as even a simple sketch will help you work through your thoughts and be clear with each trade where you want things. Agree it's not simple but it will save you loads of questions and clarify things - sections are not required other than for details not the whole building.

 

Given the cutting in with the existing roof you may want to leave that a bit open because you won't know what is under there until you get it open and if you are knocking out a big opening you should seek a Structural Engineer's design as building Control will require this.

[sarah barrows]

thanks again Mike, that's a great help.