Help please balancing specification with budget

[JohnW]

On ‎03‎/‎05‎/‎2017 at 15:11, Ferdinand said:

There is also a lot you can do tactically to stop planners gold-plating their requirements (or getting the gold-plating removed) - but that is quite tactical and situation specific, and by buying and selling (eg digger, security fencing, perhaps scaffolding) rather than hiring.

 

Lots of other aspects too, such as putting a permanent power-cabinet in once rather than having a site supply then the supplier paid again to put one into your house itself. 

 

But that is wandering off topic, so I will juts hint at that and leave it.

Ferdinand

 

Thanks @Ferdinand all good points but as we'll be using a main contractor these options will be his.

 

Edited May 5, 2017 by JohnW
Referenced user

[JohnW]

On ‎03‎/‎05‎/‎2017 at 15:28, Declan52 said:

Would go with joists either standard or I beam and forget the slab. The extra to do a floor and plus the ceiling underneath will be a big saving.

Thanks @Declan52, with teenage kids, I'm not sure that anything other than slabs will do it. It is an area that we can trim back if needed but it would be good to have slabs.

 

On ‎03‎/‎05‎/‎2017 at 15:28, Declan52 said:

200mm cavity could be reduced to 175 or 150 will save some money.

Using the Kingspan ecobead website it seems that the following fully filled cavities give the corresponding U-values;

• 150mm - 0.20W/m²K
• 175mm - 0.18W/m²K and
• 200mm - 0.15W/m²K for a 200mm cavity.

Which, would you say, is the best cost/benefit point?

 

On ‎03‎/‎05‎/‎2017 at 15:28, Declan52 said:

Cut roof or attic truss whichever suits better. Take it it's a 2 storey house and not a chalet bungalow. 

Getting the spray insulation is way more expensive than frametherm type. Plus is easily a diy job.

Yes, it's a 2 storey house with a very small roof space, about 1.7m at it's highest under the ridge. I've a family member who does spray foam insulation, so I'm hoping to get a good deal.

 

On ‎03‎/‎05‎/‎2017 at 15:28, Declan52 said:

I take it you will wet plaster the house inside. 

Bpc have kits for mhrv that aren't expensive(2k) and you can install yourself.

I have ufh downstairs and rads upstairs and it works fine.

As you are in Newcastle the ground will be gd so you can go shallow trench founds.

Realistically how much work can you/ family do???

 

 

Yes, internal walls will be wet plaster.

Thanks for the BPC pointer - I'll check it out.

UFH downstairs & rads upstairs is probably the way we will go.

I'm amazed you know the ground in Newcastle - that's class, thanks.

Realistically, I've no time and no experience in building, so it's best left to the professionals. We hope to use a main contractor to do almost everything, hence the focus on cost.

 

[JohnW]

On ‎03‎/‎05‎/‎2017 at 15:33, Bitpipe said:

UFH upstairs is dependent on how warm you like your bedrooms - our preference is on the cool side so we have no wet UFH upstairs and it was perfectly comfortable last winter - however this is in SE England, would expect NI (where I grew up) to be colder. We have wood floors upstairs so they feel warm underfoot.

 

We did however put electric UFH in the bathrooms under the tile and wet towel rads that are independent controlled.

 

Our house is near passive standard so we can get away with running the GF heating for only a few months of the year, bigger challenge is preventing overheating the rest of the year, even a cool sunny day can have you sweltering if you don't manage the solar gain properly (shading, window position etc).

 

I echo all of the above, many architects and builders work they way they're used to and don't worry too much about saving you money. If you want a good spec on a tighter budget then you need to do research, shop wisely and be prepared to do some jobs yourself where it makes sense (DIY MVHR is a popular one on this forum).

 

 

Thanks @Bitpipe, we like our bedrooms cool.

I'm interested in know why you put electric UFH in the bathrooms and not wet UFH, especially considering you have the wet towel rads.

 

I appreciate your point about shopping wisely etc... I'm hoping the main contractor I choose will be open to ideas.

 

[JohnW]

On ‎03‎/‎05‎/‎2017 at 15:50, jack said:

 

We have a very similar spec house to Bitpipe, but no heating at all upstairs.  Bedrooms are fine without, but we should have gone for heating in the bathrooms, as they get a little more nipply than ideal in winter.  

 

I'm currently planning to install a small IR panel on the ceiling of each upstairs bathroom, which should at least take the chill off the tiles each morning in winter.

Thanks @jack - having no heating upstairs would be too brave a move for me.

P.S. "...nipply in winter..." conjured up images I didn't really want to see at this early hour of the morning

[JohnW]

On ‎03‎/‎05‎/‎2017 at 16:06, Mr Punter said:

@PeterW's best suggestion was to lose the hollowcore on the first floor.  His others were good too.

Thanks @Mr Punter

[JohnW]

On ‎03‎/‎05‎/‎2017 at 16:17, jack said:

I missed the hollow-core.  Sounds an expensive build-up.

 

If you're adamant about screed upstairs, I'm pretty sure you can liquid-screed even on top of 22mm chipboard + easi-joists if you engineer it right. 

Thanks @jack

[jack]

3 minutes ago, JohnW said:

P.S. "...nipply in winter..." conjured up images I didn't really want to see at this early hour of the morning

 

You're welcome! 

[JohnW]

On ‎03‎/‎05‎/‎2017 at 16:57, AliG said:

I looked into this. It did seems that you can use screed with post-joists which might be the best of both worlds giving a solid floor and a better material for UFH, but still having a service space between the joists. There may be issues with the weight of the screed and its affects on spans.

Thanks @AliG this is something I will definitely look into as the space savings alone are attractive.

[JohnW]

On ‎03‎/‎05‎/‎2017 at 17:04, PeterW said:

If you really want or need upstairs UFH then look into something such as the aluminium spreader plates under the joists. It is a bit of fun though when it comes to the turns as you can't notch the joists so something such as the thin overfloor system may be needed. 

Thanks @PeterW what is the purpose of the aluminium spreader plate?

[PeterW]

It allows the heat to spread across a wider area than just the pipe. Works like a mini radiator. 

[JohnW]

On ‎03‎/‎05‎/‎2017 at 17:22, Redoctober said:

 

This might assist in understanding what is required for UFH and screed upstairs.

 

PW.

UFH.pdf

Thanks @Redoctober, because timber joists move, will a screed floor above not crack?

[JohnW]

On ‎03‎/‎05‎/‎2017 at 17:47, Bitpipe said:

 

We did this on our ground floor, which is suspended timber over the basement. We struggled with the loops that had to span the joist before someone had the bright idea of just bringing them over each joist and securing with a pipe clip, then cutting slots out of the 22mm OSB where the loops ran. Because we were putting another ply layer on this floor before the resin went down, it wasn't an issue.

 

I know HerbJ found a small bore wet system for his first floor that incorporated a soundproof board but it wasn't cheap. He mainly put it in for resell purposes.

 

Forgoing upstairs heat can be a bit of a leap of faith to go without so I had a few plan B's in play. The bathroom towel rads each back onto a bedroom, so a small rad could have been retrofitted back to back if required.

 

It would also be easy to add a switched fused spur to each room for an electric panel heating system, in fact our bathroom UFH was a last minute addition (we'd already started tacking) but it was easy enough to get boxes and conduit in for stats, controllers and the spurs themselves.

 

Really, if your house is well insulated and airtight, then bedroom heat requirements should be minimal.

 

Thanks @Bitpipe, totally agree that having no heating upstairs would take a leap of faith, one unfortunately that I'm not prepared to take. My compromise will be probably be small radiators upstairs and either electric or wet UFH in the bathrooms. 

[JohnW]

On ‎03‎/‎05‎/‎2017 at 21:13, PeterW said:

I plan on spending some money on a decent air tightness membrane and doing that properly to reduce the losses. 

 

I've got one room that I don't have a room below (unheated garage) but that is getting 200mm of well sealed PIR in the floor and all the garage walls are insulated so I'm hoping it will be fine. I may also put an electric panel rad in there or alternatively a heat battery in the MVHR feed. 

Thanks @PeterW, I'm still very undecided about the whole airtightness thing, based on our windows being opened frequently.

[JohnW]

57 minutes ago, jamiehamy said:

£10k for MHRV?! Are the ducts gold plated?

 that was my reaction too!!

[jack]

19 minutes ago, JohnW said:

Thanks @PeterW, I'm still very undecided about the whole airtightness thing, based on our windows being opened frequently.

 

But why are your windows opened frequently?  If it's because the house is stuffy, then with MVHR you likely won't have that concern, because the air is always fresh even when the heating's on. The only time I ever open windows is at the end of the day after a long hot spell, to let cool air through the bedrooms for a couple of hours before we go to bed.  I can't imagine any reason to open the windows in winter - the air is fresh and at a comfortable temperature, so the windows can just stay closed and do their job.

 

Even if you do periodically open windows, the MVHR doesn't care.  You lose some efficiency due to the lack of heat recovery, but it isn't the end of the world.

 

We've been living in our new house for a bit over a year.  It's the first place I've ever lived have MVHR and I now wouldn't be without it, simply from a comfort point of view.

 

I'd have thought you could get a decent system supplied and installed by your main contractor for £3-5k, depending house size and the quality of the system you buy.  I have no idea where the £10k figure comes from - even with a top end unit from someone like Paul, I can't see how you could spend that much. 

[Ferdinand]

32 minutes ago, JohnW said:

Thanks @PeterW, I'm still very undecided about the whole airtightness thing, based on our windows being opened frequently.

 

Which is a flag to invest a little more time investigating further so that you can identify the way you want your house to be built. That is something that we attempt to help with here.

 

One suggestion is to spend a few weekends away staying such in houses via AirBNB or normal B&B. At any time there are eg a number of Grand Designs houses offering B&B.

 

Ferdinand

Edited May 5, 2017 by Ferdinand

[Ferdinand]

1 hour ago, JohnW said:

 

Thanks @Ferdinand all good points but as we'll be using a main contractor these options will be his.

 

 

Unless you tell him what to do :-).

 

Particularly you may have information that he does not, or things in his standard methodology that you do not need. If you need to magic up cost savings from thin air there really is no alternative to sweating the details of the spec and build ... which is exactly what you are doing.

 

Two suggestions:

 

1 - Keep an eye on things you can do or specify which will reduce your contractor's risk, which will then feed through into reducing the extra risk premium he has to put on individual elements. 

2 - Watch for areas where you can safely go for standard rather than bespoke solutions and features.

 

Ferdinand

Edited May 5, 2017 by Ferdinand

[Ferdinand]

1 hour ago, JohnW said:

Thanks @Bitpipe, we like our bedrooms cool.

I'm interested in know why you put electric UFH in the bathrooms and not wet UFH, especially considering you have the wet towel rads.

 

I appreciate your point about shopping wisely etc... I'm hoping the main contractor I choose will be open to ideas.

 

 

In our house renovated by the previous owners have wet ufh downstairs, with rads upstairs, and Elecric ufh in the bathroom and conservatory. In my view the reasons are:

 

1 - Simpler to do upstairs.

2 - More suitable for rooms where use will be intermittent.

3 - In the conservatory we added because it was cheaper and easier for an addition, and as a "heated conservatory" selling point, and backup for the adjacent kitchen/lounge should we lose the gas.

 

We are well insulated but nowhere near passive standard.

 

Ferdinand

 

[Declan52]

58 minutes ago, JohnW said:

Thanks @Declan52, with teenage kids, I'm not sure that anything other than slabs will do it. It is an area that we can trim back if needed but it would be good to have slabs.

 

Using the Kingspan ecobead website it seems that the following fully filled cavities give the corresponding U-values;

• 150mm - 0.20W/m²K
• 175mm - 0.18W/m²K and
• 200mm - 0.15W/m²K for a 200mm cavity.

Which, would you say, is the best cost/benefit point?

 

Yes, it's a 2 storey house with a very small roof space, about 1.7m at it's highest under the ridge. I've a family member who does spray foam insulation, so I'm hoping to get a good deal.

 

Yes, internal walls will be wet plaster.

Thanks for the BPC pointer - I'll check it out.

UFH downstairs & rads upstairs is probably the way we will go.

I'm amazed you know the ground in Newcastle - that's class, thanks.

Realistically, I've no time and no experience in building, so it's best left to the professionals. We hope to use a main contractor to do almost everything, hence the focus on cost.

 

Done a lot of boreholes around the centre of town for the sewage system that went in under the pitch and putt. Plus had to do some all the way out of town for the connecting pipework. There aren't too many peat bogs around there with rock sticking out of the ground everywhere.

If it's a standard two storey then just put membrane under the truss and tape at the edges. Then put 300/400mm of rockwool in the loft and leave it. No need to spray the roof.

For the cavity the sweet spot is what you can afford. Price the three options up and see where you sit. Don't forget to add the extra cost for the different lengths of wall ties plus for a 175/200mm cavity you will need to use wider lintels or a bootleg concrete head to close the cavity which cost more.

Have you posted your elevation drawings anywhere???

[Bitpipe]

4 hours ago, JohnW said:

Thanks @Bitpipe, we like our bedrooms cool.

I'm interested in know why you put electric UFH in the bathrooms and not wet UFH, especially considering you have the wet towel rads.

 

I appreciate your point about shopping wisely etc... I'm hoping the main contractor I choose will be open to ideas.

 

 

Our bathroom UFH was a bit of an afterthought, first fix was almost complete so electric was the only option - floor deck had been laid at that point. 

 

I'm sure that a wet system would have worked fine, we did faff about a bit with the bathroom layout after the frame was complete but before first fix so would not have known this in advance - would have caused issues during first fix with foul runs, cutting into floor etc. - you also don't want UFH under baths or shower trays as it dries out the trap and can cause smells.

[Bitpipe]

4 hours ago, JohnW said:

Thanks @Bitpipe, totally agree that having no heating upstairs would take a leap of faith, one unfortunately that I'm not prepared to take. My compromise will be probably be small radiators upstairs and either electric or wet UFH in the bathrooms. 

 

It's cheap to make provision during first fix and then decide if you need it later. When you have finalised your u values, I'd advise calculating your heat demand as that can be quite revealing. 

 

Jeremy has a simple spreadsheet that will give you a good idea, you can also do SAP or PHPP modelling if you want to get more precise figures.

 

Also, don't fall into the trap of only thinking on heating - it's the obvious concern (especially in NI) given all of our experiences with poorly built and draft homes. I can guarantee that if you build to the standard you're planning to, overheating will be just as big a concern and this is more difficult to counteract (opening a window in a hot house on a hot day makes no difference).

 

Think also on your likely solar gain, house and window orientation, shading (trees, neighbours etc) - all of this can be modelled and mitigation planed. For example, we have electric external shutters on all east windows (where we face the street) and on east and south Velux. Makes a big difference to preventing overheating. There is one ground floor south window we omitted to get blinds on as we though the neighbours gable would block the sun - turns out that when the sun is low (spring & autumn) it shines right in so we now need to mitigate that another way.

 

[Bitpipe]

4 hours ago, JohnW said:

Realistically, I've no time and no experience in building, so it's best left to the professionals. We hope to use a main contractor to do almost everything, hence the focus on cost.

 

 

A large number of the self builders here started out with zero knowledge but do not assume that professionals know it all and will make good decisions on your behalf or want to save you money - not because they're bad people but they all have a set way of doing things and know what they know - architects are as guilty of this as anyone, ours designed a pretty house but was adamant that a basement would be a disaster (best feature in the house) had had zero idea of low energy building principals or exposure to materials other than brick and block.

 

If you really want to focus on controlling cost then you need to understand and if necessary question every design decision, why they have been made, what the alternatives and tradeoffs, are you're getting a good deal or being ripped off etc..

 

Also, a main contractor will also charge you 20-30% premium to effectively manage the sub-contractors and cover his other overheads, you may consider this value for money but I did not. You also have no control over the quality of the subs and may not see what's going on day to day.

 

With some commitment (wife and I both work, have kids etc) we acted as the PMs and chose competent subs to undertake the works - helped by using packages for the big critical complicated elements such as groundworks and frame to watertight / airtight. Is occasionally stressful but probably no more than watching a contractor build your house and make potentially expensive decisions for you!

[ragg987]

16 minutes ago, Bitpipe said:

A large number of the self builders here started out with zero knowledge

Count me in to that. Made a few mistakes along the way too - all part of the learning.

18 minutes ago, Bitpipe said:

not because they're bad people but they all have a set way of doing things and know what they know

Agree, and would also add that they are not going to make the best material purchasing decisions for you as (in my experience) they do not plan further ahead than a few days, and just rely on the local builders merchant to supply whatever they normally supply. After all, they can simply pass the cost on to you. This was one key area I took control of and I found I could easily better the builder for prices or specification, sometimes by as much as 50%. But I drew the line at nuts and bolts etc where I let the builder get on with it.

 

As @Bitpipe, you will need to understand the detail if you decide to do this.

[Bitpipe]

I can't recall if it was said on the Mark Brinkly Self Builders Bible (you should own this ) or on eBuild but the priority of the contractor is cash flow and credit, not discounted prices.

 

So, assuming they charge everything through to you (or have budgeted to do so), they won't waste time haggling or deal hunting - the real value of a BM to a contractor is credit and payment on account.