Detailed design plans or not?

[gc100]

Hi all,

 

I'm considering whether to spend time and money with the architect and draw up detailed plans and then pay a QS to do a form of bill of quantities, so that I can try and take all the risk out of the project in terms of cost. My thinking is if we go down this route then we should know what the build will cost before actually spending any large sums and being too late to change things. It will delay the start of the project a little, as they are saying it would take them about 4 months to do vs 2 months for building regs plans.

 

Has anyone else gone down this route? What was your experience?

 

Thanks

[Ferdinand]

Welcome to the forum.

[AliMcLeod]

57 minutes ago, gc100 said:

so that I can try and take all the risk out of the project in terms of cost

 

I'm sure you already know this, but doing this will never "take all the risk out of the project in terms of cost". It would be very surprising to not have unknown unknowns. It just takes the architect to not included something in their detailed design or you to have a problem during the build (eg, getting out of the ground, connection to utilities) and your contingency could be gone in a flash.

Edited November 23, 2018 by AliMcLeod

[gc100]

50 minutes ago, Ferdinand said:

Welcome to the forum.

Thanks

[gc100]

7 hours ago, AliMcLeod said:

 

I'm sure you already know this, but doing this will never "take all the risk out of the project in terms of cost". It would be very surprising to not have unknown unknowns.

 

Yes I should have written: ..reduce the risk..

[mvincentd]

I can only speak from the experience of a single self-build  but the lack of true detail in my building regs drawings has resulted in ongoing pain and expense.  Maybe its just because my house is non-standard (but I doubt it as most self builds are) but the B-Regs drawings are woefully lacking and assume 'the builder will know how'..but he won't!

The 2 extra months for enhanced drawings can easily by clawed back by actually knowing what you're building compared to guessing day after day!

[Stones]

@gc100  Welcome to the forum.  It's certainly one strategy, although bear in mind, architects and QS's can make mistakes (+/-) as well.  I've built six houses, and for 5 of them, tendered using build reg drawings.  For our most recent house, I used the planning drawings to tender.  With each set of plans I provided a detailed list of specifications covering everything I could think of, from shelves in wardrobes, to specification of slabs to be laid.  No reason why you couldn't do the same yourself?

 

 

[the_r_sole]

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Edited September 26, 2019 by the_r_sole

[gc100]

Thanks all.

 

On 23/11/2018 at 20:26, Stones said:

@gc100  Welcome to the forum.  It's certainly one strategy, although bear in mind, architects and QS's can make mistakes (+/-) as well.  I've built six houses, and for 5 of them, tendered using build reg drawings.  For our most recent house, I used the planning drawings to tender.  With each set of plans I provided a detailed list of specifications covering everything I could think of, from shelves in wardrobes, to specification of slabs to be laid.  No reason why you couldn't do the same yourself?

 

 

 

Its a possible of course hence the post. Are build isn't really a 'standard house' - its a barn conversion ( with extension if the planning committee says yes in 2 days time!). I want to achieve high air tightness and I just don't know if the local general builders will really know what they are doing. 

 

It seems its worth doing, but its at a cost. I don't suppose it will save anything other than giving us a much better idea of the actual cost of the build before we start.

 

On 23/11/2018 at 20:50, the_r_sole said:

Coming from this from a slightly different view... Building reg drawings are only to prove compliance with building regs, they aren't tender or construction drawings and if you use them as such you're not going to get accurate build costs.

4 months for what, the architect? The qs? Seems like huge timescales for either tbh

 

What plans did you use?  4 months for the architect - I've spoken to 2 or 3 and they all say the same in terms of timescales. Mainly because it involves other consultants such as structural, electrical, window suppliers, etc and introduces lots of waiting. I'm sure its not actually more than 40 hours work.

[PeterW]

With a conversion you’re even less likely to design out the unknown unknowns unless you have a very extensive survey done which would probably be just as well spent as contingency. 

 

Any builder taking this on as a firm or fixed price will just load up the pricing to cover the risk anyway. 

 

If you want decent airtightness for example, go with a contract that has a maximum value you will expect on a blower test and give that to the builder - he doesn’t get paid a certain amount until that’s delivered and it covers everyone. 

 

 

[the_r_sole]

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Edited September 26, 2019 by the_r_sole

[gc100]

2 hours ago, the_r_sole said:

 

If you have building regs drawings do you not already have the majority of that information in place?

 

 

We only have the planning plans at the moment. No building regs or anything.

[Gav_P]

Having just finished my build, which I only used PP drawings, I would get detailed drawing done. 

 

The cost of them should easily be balanced out by reducing errors, late changes, better fixed cost from builders, stress etc etc etc