Viability of shell only

[SE22Reno]

I’m planning a loft conversion, rear extension and substantial renovation of a Victorian house in London, and I’m trying to sense-check whether some form of shell-only or hybrid main contractor arrangement is realistic.

 

By “hybrid”, I mean a builder taking on the main structural/building works and other agreed core items, while I separately procure some specialist packages and selected internal works.

 

About me

 

I have a day job, so I cannot be on site full time. I can commit some time to managing the project, but probably not as much as would normally be needed for a pure shell-only/self-managed route.

 

However, a close friend, who I trust, is a self-employed carpenter and runs a carpentry/renovation business with his business partner. They do not normally operate in my area and they do not have the experience/capacity to take on the whole project, but they do have good experience working on renovation projects. My idea would be for him to take on the elements he is comfortable with and help me coordinate some other packages.

 

Why I am considering this route

 

Cost is obviously one factor, but the other reason is that I have already identified a number of packages/trades that I am likely to procure separately, mostly specialist items. These include:

 

• cellar waterproofing/tanking;
• potentially cellar dig-out/underpinning, if not within the builder’s scope;
• ASHP and UFH throughout the property, by a heating specialist;
• windows and steel rear doors;
• wood flooring, at least to the ground floor;
• kitchen fitting, likely by the kitchen supplier;
• solar, batteries and EV charger.

 

I have also found a plasterer and decorator. My carpenter friend should be able to carry out a lot of internal carpentry and fit-out work, potentially including internal stud walls, plasterboarding, insulation, doors, architraves, skirting, boxing, access panels and similar works, subject of course to agreement with the main contractor and Building Control requirements where relevant.

 

On electrics, I have found two potential electricians that I would like to use. I understand that electrics probably need to be treated as one coherent package, with one electrician responsible for first fix, second fix, testing and certification.

 

My reservations

 

The biggest gap is bathrooms. My carpenter friend is not comfortable fitting bathrooms out, and I am not sure I want to leave bathrooms as something to find a separate trade for later. My instinct is that, even under a hybrid route, I would need the main builder to take responsibility for the bathrooms and associated domestic plumbing.

 

I would also want the main builder to own certain key items, such as the roof/external envelope, flat roof build-ups/VCL/weathering, main structural works, and ideally the staircase into the loft. I could possibly source a staircase specialist, but I would rather not add another separate package.

 

Generally, I do not mind that this route will cost me more time (though, as I say, I'd hope my friend can take some of this burden) but I would not want to do it if it prolongs the build by a lot (if it takes me a few extra months, that's fine, but if it takes an extra six months that would be a problem).

 

What I am trying to work out

 

I am trying to work out whether it is realistic to find a builder who would be happy to take on a defined main contractor package – structure, shell, roof/envelope, weather-tightness and selected core items such as bathrooms/plumbing – while allowing me to procure some specialist packages and internal works separately.

 

I would be grateful for views from anyone who has done something similar, or from builders/PMs who have been on the other side of this kind of arrangement.

 

Thanks in advance.

 

 

 

[Bancroft]

Thoughts from an amateur learning as I go...

We're doing similar to you but on a bigger scale.  We've contracted a main contractor to do the groundworks, slab and ICF build for a new house.  Were now preparing for phase 2 - everything else.

 

Things that have come up/been discussed with the architect and other thoughts:

 

• Check the Building Regs.  Something this big may need a designated main contractor/duty holder.  This could be you but be aware of what your responsibilities might be as a result.
• A main contractor will probably cost more but could save money by being more efficient and less stressful.  If you sequence a plumber to come in on Tuesday after the electrician finishes on Monday - but the electrician doesn't - then you're left holding the baby.  That will probably make you more likely to build gaps into the timeline which, in turn, will increase grief and nausea from the other half because things drag on so long.
• If you do use a main contractor be ready to have lots of discussions as to why you want the Heat Blaster 3000 heat pump while the MC insists on the Gentle Waft 5000 - because that's what he's always fitted.  When I told a Tesla Fan Boy electrician I would not be having anything with the word Tesla on it in my house on principle his face was a picture of 'does not compute...'
• Boundaries and responsibilities - if you're going to get different people in to do all the different jobs, how are you going to get any of them to take responsibility when something goes wrong?  The roof leaks and knackers your new MVHR - who pays for the new MVHR?  Probably easier to get an answer if one MC was responsible for the whole lot.

 

I think there are three key elements here - time, cost, risk and only you can understand the importance of each one.

We're going down the MC route because of the size of our project but there's part of me that wants to be the one in charge - because this will be our forever home but, as far as any builder is concerned, for them it's just another job to be forgotten about in a few months' time.

 

Whichever way you go throughout the contract, by all means delegate but never abdicate.  As soon as you take your eye off the ball, or allow someone else to do things in ways you wouldn't, then you're opening the floodgates to ending up with something you didn't want.

[Conor]

Bancroft had it well covered, my view as a self builder and as a project manager as a day job.

 

Avoiding a main contractor and managing the build yourself will save you upto 30% of project cost. BUT...

 

Getting trades will be tough.

You take more responsibility and risk.

It takes a LOT of time as you have to learn and do at the same time.

It's much more satisfying.

 

The key thing is to make sure roles, responsibilities etc are clearly defined.

 

"However, a close friend, who I trust, is a self-employed carpenter and runs a carpentry/renovation business with his business partner. They do not normally operate in my area and they do not have the experience/capacity to take on the whole project, but they do have good experience working on renovation projects. My idea would be for him to take on the elements he is comfortable with and help me coordinate some other packages."

 

I would absolutely not do this. Recipe for disaster. Grey lines. No cost control, you take all the risk. You'll fall out when something goes wrong.

 

Much more to it than this but I've no time to say more right now. Something that you'll soon be familiar with 🤣