How much cheaper is a pre-fab house?

pathway33

A 1000 sq ft bungalow. How much cheaper would it be pre-fab than built on site ? What can go wrong with a pre-fab?

thanks

muffler

Are you talking about a pre-fab as opposed to timber framed construction?

pathway33

pre-fab yes. Not timber framed. Pre-fab as in it is delivered to a prepared site in about 5 pieces and assembled on site in one day.

inchbyinch

I don't think it is cheaper in fact i would imagine it might be a little more expensive!

Pros,
Time on site,
shop floor quality build,
Insulation standards are normally much better (have been machine installed so better installation)

Cons,
flexibility after design.
expense

Its a personal choice after that. If you look at Grand designs website they have had some factory built units constructed.

rgds
Inchy

muffler

They aren't much more than a quick fit solution for a housing need. Short life span so Id suggest you go for something more traditional.

lanod2407

Muffler ..... what do you mean when you say "short life span"?

muffler

Compared to a bricks and mortar house you would probably expect them to have less than 50% of the lifespan.

Let me point out something to you. Homebond (who provide a 10 structural guarantee on new houses) have stated that a blocks/brick and mortar house would have an average lifespan of 70 years. A timber framed house would have an average lifespan of 35 years and while they would not provide any guarantee on pre-fab houses Id think its safe to assume that you are looking at somewhere in the region of 20 - 25 years before you find yourself in the position of having to carry out major improvements. Thats my opinion.

lanod2407

Interesting stuff - I'm interested in finding out more about the lifespan of pre-fabs ........... I've seen a couple of pre-fabs where the walls are custom-made concrete walls, built to the clients' specs, with insulation, service conduits, etc etc included in the fabrication. What would make the lifespan of these types of structures so much shorter than, say, a standard block and mortar house?

........ I'm asking purely out of curiosity - interested in understanding the backgrounds to the differing lifespans for future reference.

sydthebeat

an important fact to remember about pre-fab houses is that they must be accompanied by proper certification to show that they comply to all irish building regulations. Many fail on this issue.

muffler

Im sure some of the other guys here will express their opinions also.

lanod2407

Muffler - what's behind your opinion that pre-fabs lifespan is circa 20-25 years?

muffler

lanod2407 wrote: »

Muffler - what's behind your opinion that pre-fabs lifespan is circa 20-25 years?

I've stated that above.

Poor Uncle Tom

A 'pre-fab' house is not necessarily a specific given item, all it means is the house is Per-Fabricated before coming onto the site. They can be constructed in concrete, timber or steel or any of the futuristic polys' out there or indeed any mixture of the above.

The pre-fabs I remember are the ones from the early seventies, Concrete foundations, poured deadwork and slab (I remember the hardboard boxes which were grouped and fixed together and had the concrete poured over), bolted concrete panels, trussed roof, timber windows, concrete tiled roof. Traditionally in bungalow format, huge windows, dash finish, easily distinguisable with the rectangular mastic lines dividing the walls in the elevations.

These are still up today around the country. Very durable, very badly insulated and very thin walls (70mm). Most have had all the windows changed, some have even been extended. Very hard to cut through the concrete panels (like flint).

They were designed so small that when bought in recent years most were knocked and replaced rather then extending and using.

Modern pre-fabricated structures are very much composite in nature and therefore the equivolent of being vacuum packed. If timber is an element of this composition I'm afraid Muffler is correct about its lifespan. If an element of a composite structure is compromised then the entire structure is under question. (you can tell I am not a huge fan of timber frame).

There are other types of pre-fabs out there, lets see how they do over time.

lanod2407

muffler wrote: »

I've stated that above.

Maybe it's me - but I don't see anything above to support an opinion that precast lifespan is 20 - 25 years.

gooner

I visited a couple I know that had just taken delivery of a pre-fab house,which arrived on site in 2 halfs.It had basically everything fitted out when it arrived,all first and most second fix carpentry,electrics,central heating and plumbing including kitchen and bathroom suites,etc.Apparently you can get them to include as much or a little as you choose in the fitout.For example this couple did all the tiling and wooden floors themselves.But you can get them to include these,they will even hang the curtains.The guys father had bought one over 10 years earlier and was very happy with it.Everything looked to be fabricated to a very good standard,with plenty of insulation and double glazed upvc windows and doors.They had just finished building the outer walls themselves using concrete blocks,so it was pretty much like a standard timber frame.The house itself seemed to be raised above the ground and I think the idea was that air could circulate around the outside of the house,but the block outer leaf went all the way to the ground.According to the couple the price was excellent,much lower than any conventional build including timber frame.I have no connection with this company,I have just been in one of their houses.

http://www.westernparkhomes.com/builtaround.htm

Theirs was a "48 x 24 incl utility"