Home Extension - Advice/Recommendations?

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tchart

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#271909 1-Jun-2020 10:18

Hi, I searched the forums but couldnt find any good threads (or they were really old).

We are looking to extend our house. While its a major extension in reality its only "slapping on" a large rectangle to the existing house but would include modify the roof, include a new bathroom etc.

We contacted our original builder a franchise that does new builds (house is only 4 years old) and they dont seem interested.

We also contacted a renovation franchise who basically said we need to give them $5K up front to do a design and have a quanity surveyor do a good estimate.

While that makes sense I'm hesitant to spend $5K if they come back and say its half a million.

Anyway, has anyone undertaken a largish house extension? If so who did you go with? A franchise? An independent builder?

Im in Wellington (Hutt Valley) if that helps.

nickb800

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#2496060 1-Jun-2020 11:22

Probably fair to charge for design before giving any cost estimate, extensions/alterations can be a black hole. We are about to start an extension - have had a draughtsman draw up plans and I'm building myself. I think it was $1500 for concept drawings and $4000 for consent drawings. I'm not sure you could really quote off the concept drawings.

Average new build costs start at something like $3k per m2 - perhaps work on an assumption of say double so $6k for an extension to get an idea of budget. If that number is feasible, then get design drawn up. Builders will quote off consent drawings for you. Also worth noting that Placemakers and the like have quantity surveyors who will work off your plans and provide free quotes on materials (if you want to go for a labour only contract)

Jase2985

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#2496070 1-Jun-2020 12:09

for an extension budget $3000-4000 per sqm outside of any design work or consents

also find out weather what you plan on doing will require resource consent, and if so what impacts that may have to the cost.

tchart

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#2496071 1-Jun-2020 12:20

Jase2985:

for an extension budget $3000-4000 per sqm outside of any design work or consents

also find out weather what you plan on doing will require resource consent, and if so what impacts that may have to the cost.

Thanks, this is kind of what I was after. Gives me a good ballpark figure.

tchart

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#2496073 1-Jun-2020 12:24

nickb800: Probably fair to charge for design before giving any cost estimate, extensions/alterations can be a black hole. We are about to start an extension - have had a draughtsman draw up plans and I'm building myself. I think it was $1500 for concept drawings and $4000 for consent drawings. I'm not sure you could really quote off the concept drawings.

Average new build costs start at something like $3k per m2 - perhaps work on an assumption of say double so $6k for an extension to get an idea of budget. If that number is feasible, then get design drawn up. Builders will quote off consent drawings for you. Also worth noting that Placemakers and the like have quantity surveyors who will work off your plans and provide free quotes on materials (if you want to go for a labour only contract)

Thanks. Yeah no problem with the $5K if I know we will proceed. So $3-4k per m2 is what I was looking at

BTW $6k seems a bit OOT - thats looking like half a million for what we were after. You could build an entire new house for that.

blackjack17

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#2496074 1-Jun-2020 12:25

Jase2985:

for an extension budget $3000-4000 per sqm outside of any design work or consents

also find out weather what you plan on doing will require resource consent, and if so what impacts that may have to the cost.

It is an extension that has a bathroom. It will be more than $3000-$4000 /sqm.

We looked at converting a 10 sqm conservatory to a real room and priced it out, materials only at trade rates to be roughly $10,000 without consents, stopping, electrics, or carpet.

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Jase2985

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#2496086 1-Jun-2020 13:17

blackjack17:

It is an extension that has a bathroom. It will be more than $3000-$4000 /sqm.

We looked at converting a 10 sqm conservatory to a real room and priced it out, materials only at trade rates to be roughly $10,000 without consents, stopping, electrics, or carpet.

maybe maybe not, our garage is coming in at @2000 per sqm, and we have done a bathroom/toilet renovation for somewhere in the middle of that range. remember big open rooms will be a lot lower while smaller rooms like bathrooms will be higher so they average out.

Froglotion

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#2496098 1-Jun-2020 13:43

Aim for a company that specialises in renovations. You don't tend to find builders that do new housing AND renovations. They tend to stick to one of the two. If you speak to the companies that deal with just renovations, you'll be working with people that know all the ins and outs. Will end up being cheaper as they have streamlined processes in place and contractors they work with frequently.

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nickb800

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#2496224 1-Jun-2020 16:53

There's a bunch of factors which will determine where in the price range you sit
- Can trucks access the extension or will everything need to be carted by hand
- What is the ground contour like - can you just pour a slab or will it need cut/fill and/or piles
- How extensive are modifications to existing house/roofline to interface with the extension
- What standard of finish/fittings
- Proportion of intensive/extensive areas e.g. bathrooms vs living rooms

You mentioned Wellington so I assumed worst case for ground/access :)

Handle9

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#2496267 1-Jun-2020 17:43

You've got a couple of options.

You can work with an architect / designer and get plans drawn up. You will have to pay for this up front but you then get the ability to go to the market and price builders competitively.

The other option is a builder to design and build. If the builder is charging you up front for concept drawings then you should own these and be able to use these to get multiple prices. If they want you to pay but they retain ownership of the design then tell them to take a jump.

If you give a builder a brief they should be able to give you a budget estimate +-20%. Do a quick sketch of what you are looking for along with basic specs. Given your house is new it could just be "to the same standard as existing".

The market for builders will get better so don't be afraid to wait.

Also, and most importantly, don't sign anything a builder gives you without getting a property solicitor to look at it and comment. If you aren't confident with contracts or can't deal with confrontations don't try and save $5k on legal fees. It will likely bite you in the end. Their "standard" contract won't offer you anything approaching fair protection, it'll be heavily weighted in their favour.

Stu1

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#2496284 1-Jun-2020 19:12

Went through process recently design, plans, engeering and resource consent just over 10k hutt valley region . SQ meter cost 4k. Need to be carefull with builders quotes we proceeded with final design plans based on 30 percent varience in costings , final quote came in 50% higher than first quoted so put on hold. Most expensive papers i will ever own 10k of costs with nothing to show for it. Good leason learnt.

neb

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#2496947 2-Jun-2020 17:35

Jase2985:
for an extension budget $3000-4000 per sqm outside of any design work or consents

Was just chatting to a friend of mine who moved back to North Dakota from NY just as things were getting scary with Covid19, and is now considering staying there full-time. He mentioned among other things that there's no consent process, you just build whatever you want (I assume there's still a requirement to meet fire codes and similar).

Oh, and his property size is "you can fire a gun in any direction without hitting anyone".

tchart

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#2497233 3-Jun-2020 09:46

Stu1: Went through process recently design, plans, engeering and resource consent just over 10k hutt valley region . SQ meter cost 4k. Need to be carefull with builders quotes we proceeded with final design plans based on 30 percent varience in costings , final quote came in 50% higher than first quoted so put on hold. Most expensive papers i will ever own 10k of costs with nothing to show for it. Good leason learnt.

Thanks @Stu1 very interesting. So was the quote +50% and then looking at +-30% variance?

Stu1

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#2497327 3-Jun-2020 12:52

tchart:
Stu1: Went through process recently design, plans, engeering and resource consent just over 10k hutt valley region . SQ meter cost 4k. Need to be carefull with builders quotes we proceeded with final design plans based on 30 percent varience in costings , final quote came in 50% higher than first quoted so put on hold. Most expensive papers i will ever own 10k of costs with nothing to show for it. Good leason learnt.

Thanks @Stu1 very interesting. So was the quote +50% and then looking at +-30% variance?

We had concept plans drawn up got a quote of that . I thought add 30 percent on to that worse case. We had final plans and consent done final quote was double the original quote. Wasn’t economical to go ahead.