extension block work price

Dave 101

as the title says, block work price for a 3.5m x 5 m extension which includes foundations and concreate floor.

good access end of terrace, blocks could be dropped direct on site

Four Phucs Ache

Prepare site
Clear site
Move drains?
Relocate waste pipes?
Dig thrench 1m or 3m??
Remove waste fill
Dwarf walls or tench fill?
70c blocks or 2 euro aero blocks??
Underfloor heating above slab?
100mm , 300mm cavity or external insulation?
Any steel required to open existing room?


Sorry if I seem forward but I'm doing something similar soon !

Top of my head if meeting regs for foundation slab and walls for your size...if very straight forward and no surprises below......14

Dave 101

Four Phucs Ache wrote: »

Prepare site YES
Clear site YES
Move drains? NO
Relocate waste pipes? NO
Dig thrench 1m or 3m?? 1
Remove waste fill NO
Dwarf walls or tench fill? TRENCH FILL
70c blocks or 2 euro aero blocks?? 70C
Underfloor heating above slab? NO
100mm , 300mm cavity or external insulation? 100MM
Any steel required to open existing room? YES


Sorry if I seem forward but I'm doing something similar soon !

Top of my head if meeting regs for foundation slab and walls for your size...if very straight forward and no surprises below......14

yes its a very straight forward build as I know, steel required 3m

Four Phucs Ache

Is the steel required on the new construction for a slider/ bifold or opening up the existing rear wall?

Dave 101

Four Phucs Ache wrote: »

Is the steel required on the new construction for a slider/ bifold or opening up the existing rear wall?

open the existing rear wall ? currently only a small single door

Four Phucs Ache

If your end of terrace, I imagine your width is 5m and your are building 3.5m out.

Steel wouldn't normally be required for a roof 3.5m long unless the steel is being used for the ridge of a pitched roof?...again correct grade 7x3 or 9x 2 rafters would suffice.

Are you opening up the kitchen ?.. If so the steel would hold up the bathroom and bedroom above to create an open plan area for your new works involving removing some of The existing rear wall??

Dave 101

Four Phucs Ache wrote: »

If your end of terrace, I imagine your width is 5m and your are building 3.5m out.

Steel wouldn't normally be required for a roof 3.5m long unless the steel is being used for the ridge of a pitched roof?...again correct grade 7x3 or 9x 2 rafters would suffice.

Are you opening up the kitchen ?.. If so the steel would hold up the bathroom and bedroom above to create an open plan area for your new works involving removing some of The existing rear wall??

opening up the kitchen and removing rear wall

Four Phucs Ache

As per orig post so for just foundation, slab and new insulated walls, remove existing rear wall and install a designed steel....circa 20k

For the roof, whether flat or pitched with velux etc
External and internal rendering / plaster
Decorating and making good the removed wall
Plumbing, electrics etc...circa 15 k

If doing a lot of work yourself obv you can take a chunk off above

Dave 101

Four Phucs Ache wrote: »

As per orig post so for just foundation, slab and new insulated walls, remove existing rear wall and install a designed steel....circa 20k

For the roof, whether flat or pitched with velux etc
External and internal rendering / plaster
Decorating and making good the removed wall
Plumbing, electrics etc...circa 15 k

If doing a lot of work yourself obv you can take a chunk off above

Sound man, thanks for all the help ðŸ‘

Four Phucs Ache

Four Phucs Ache wrote: »

As per orig post so for just foundation, slab and new insulated walls, remove existing rear wall and install a designed steel....circa 20k

For the roof, whether flat or pitched with velux etc
External and internal rendering / plaster
Decorating and making good the removed wall
Plumbing, electrics etc...circa 15 k

If doing a lot of work yourself obv you can take a chunk off above

EDIT: Sorry, I misread your post. I thought you were saying €15k all-in. But I see that you're actually saying €35k? (which seems more realistic).

Four Phucs Ache

Yeah kkv roughly 35 or so for 17.5 Sqm basic build.

I Know of one build recently though of 25 sqm involving a 5m steel , a triple track slider and a top notch kitchen came in at 65k.

A good chunk of the cost was the kitchen which included a secret extractor fan and Italian marble and large auto velux windows.

Well I built an extension last year. Can't recall what the overall square meter sizing is on it, to be honest, but I'd guess it works out about 35-ish square meters (I use the 'old' currency - it's about 10ft to the back, and the extension is wider than the house itself, at approx 30ft. Then the overhang at the side of the house returns in an L shape to give a side extension that's about 5-6ft wide, and about 15ft long).

Which, my basic/poor grasp of maths tells me is about 390sq foot, or 35sq meters.

I paid about.. pfft... 50k, I'd say. Which included the garden being redone (about 45sq meters, paved). I cut corners everywhere I could (but never without doing a lot of research first, to make sure my corner-cutting wouldn't backfire on me).

For example, I saved a lot of money by building with cavity blocks instead of doing a cavity wall. Any mention of this to people was met with scorn and 'you'll have damp everywhere', but I googled, and researched extensively, and visited about half a dozen extensions built with cavity blocks (some built in the last year, and some about 10-12 years old) and none of the owners had any real issues or complaints about it (same builder).

I also went with a flat felt roof which saved a few euro (although I didn't have a whole lot of choice there, i wouldn't have gotten a great angle on the roof anyway, as it would possibly have hit the upstairs windowsills to try and get a decent angle, and i knew i wanted a flat roof as i preferred the look of them. The plan was a fibre glass flat roof, but that changed as i went looking for details and info about fibre glass roofs. Heard some bad things about creaking and banging noises as they can be affected by temperature, and decided that the best route was to go with the tired and tested torch on felt, which i again researched a lot. I saved about €500 doing this, though that decision wasn't a money-saving decision).

Tiled or slated roof would probably cost more (though I'll possibly get rode by the insurance companies going into the future with my large flat roof).

So there are savings to be made if you're willing to cut corners like I did, but as you're adding to a house, and not spending money on a throwaway product (ie; you're stuck with this) you have to make decisions that you're happy and comfortable with.

The only real cost-saving measure I went with, that I do regret, was building the side extension bathroom, with only an extractor fan, and no window. Now I'm looking to, at some point in future, get rid of the fan and stick a window in, instead, for a bit more ventilation and to let some natural light in.


I hired a general handyman style of builder. Chap that works on his own with one or two regular lads with him, but who knows a lot of the tradesmen as friends in the area and could give me their info, or let me pick who i wanted (most of his contacts were cheaper than random people i found locally, with a few small exceptions, but all were qualified/registered and such, no cowboys were near the place).

Rather than going with one of the bigger companies. This ultimately saved me a lot of money, I'm sure, but more than that, it meant that I could chop and change the plans along the way without 20 people sitting around for a day scratching their hole, being paid, whilst I discuss a new idea with the 'boss'. I ultimately didn't make that many changes, but any that I did make didn't cause too many issues as the builder was never upset or annoyed (presumably was happy with me changing things, as it would be an extra few euro in his pocket working on the job a bit longer).


Sorry, I'm just rambling on now. But when i was starting to get into the idea of building my extension, I loved reading about other people's, and trying to see how others approached it, so i tend to waffle on a lot about it incase it ends up being helpful haha