eoinsgaff in the process of designing my own house

[eoinsgaff]

I'm in the process of designing my own house. My intention is to get as close to a 'passive haus' as possible while still remaining economical.

Whats of note is the type of insulation that will take a structural load - 300KN/m2 I think. This allows one to have a foundation pad, draining aggregate, 300mm of insulation and a concrete slab. The floor is then 100% insulated from the ground below without the nned for any for of cold bridging.

The building walls (timber frame or similar) can be supported on the concrete slab and further external insulation attached to the outside of the timber frame then laps down outside the concrete slab to meet with the 'ground insulation'.

Continuing this across the roof gives a very sustantial 'U' value for the structure.

If there are any concerns with the loading on the 'ground insulation', Poroton type blocks can be used to take said load.

Of course this 'airtight lunchbox' needs ventilation.

I must try to upload a few typical sections if anyone is interested.

Eoin

 

[MikeG.]

Eoin,

start a new thread! This is clearly an interesting subject, but seperate from the shed build. I'm keen to see what you have in mind.....

Mike

 

[eoinsgaff]

Mike,

Will do. I thought it might have been an idea for the base of Paul's structure.

I haven't got enough info together yet for a new thread but I will in due course.

Eoin

 

[Steve Maskery]

I must try to upload a few typical sections if anyone is interested.

I think you'll find lots of interest! Yes please.
S

 

[CNC Paul]

Hi Eoin,

The reason for going down this route is that I am try to develop this method of construction for a passive house in Waterville, Co Kerry, where abouts in Kerry are you ?

My shed/studio is just a practical way of testing my initial idea.

I look forward to seeing your typical sections.

 

[MikeG.]

Careful with the terminology guys........"Passive House" doesn't mean very much. Are you aiming to be autonomous, zero energy, zero-carbon emitting, autartik, off-grid or the like? That I understand............Passive means nothing to me. "Passive" is usually used in conjunction with "solar" to mean taking advantage of solar gain for reducing space heating requirements.

I would also humbly suggest, having built 6 or 8 of the most energy efficient above ground houses ever built in the UK, that there is little likeliehood of achieving near-zero space-heating requirements with this lightweight construction. You really do need thermal mass within your insulated envelope to get anywhere near.

I also suggest we start this conversation again in a new thread! Maybe we can get a friendly moderator to cut and paste these postings.

Mike

 

[DaveL]

I cut the end off the old thread into this one, I hope that is OK?

 

[houtslager]

well imho a good way to start this idea is to think about using small straw bales for the walls and using lime render on the exterior, which iirc is readily available in Eiré. This would also give your house a lot of character too

Ok, people may think your mad, but you won't be the first in Eiré to use this old technology.

PM me if you want more / or specific data.

hth,

HS

 

[big soft moose]

well imho a good way to start this idea is to think about using small straw bales for the walls and using lime render on the exterior, which iirc is readily available in Eiré. This would also give your house a lot of character too

Ok, people may think your mad, but you won't be the first in Eiré to use this old technology.

PM me if you want more / or specific data.

hth,

HS

Personally I like the strawbales for the mass of the walls but i would build a timber frame and skin and just use the bales for insulation and inner walling - rather than having them take a structural load.

Also be aware that using non standard materials can make it harder to get both PP and insurance.

At the end of the day we can all talk it here but a lot is going to depend on the nature, shape , location, and accessibility of your site - Do you already own the plot ? or are you just in the plot search phase ?

 

[eoinsgaff]

Ha ha, Ok Guys, I've been politely but forcibly been nudged into a new thread. I must pull some stuff together for you to see what I'm aiming at but the overall concept is as follows:

The Passive Haus Institute in Germany promotes a build pretty much what you have described Mike. The house is 'super insulated' and airtight to the point where the heat from the light bulbs is enough to keep the house warm. A mechanical heat exchanger keeps the air fresh without venting heat and the house is orientated to make maximum use of the suns light - primarily through the houses windows and secondarily with solar panels.

Of course I've a better way of doing it. OK, maybe not. The Passive Haus Institute designs give maximum benefit but with little heed to cost. My goal is to achieve an optimum ratio of cost and benefit. In other words the most benefit from the least cost.

Eoin

Oh, and a workshop. A decent workshop. I'm currently working from a bench in a bedroom and a few machine tools in a cold shed. Priorities lads, we must keep our eye on the ball... :-k

 

[houtslager]

Well I have built 3 types of SBbuildings - traditional [ if one can say thatfor a technology 150 yrs old ] timber frame with SB infill and a hybrid [ mainly load bearing sb with secondary support from a timber frame.

Out of the three, I prefer LB SB, but for speed and peace of mind for the non adventurous a timber frame with SB infill.

This allows a roof to be put on, and the SB stored underneath, whilst one waits for a team of people to help build the bale walls, and a couple weather days lol [ In Eiré ???]

Then, one can lime render the outside straight away with a "harling gun" or, batten out, membrane out, batten out again and then clad in any material that fits in with the surrounding architecture.

Inside, there are many possibilities, favourite ones are with either clay plaster or again with lime. See Ben Law's build on C4 Grand Designs.

Or, board out using 4 by 2's to create an air gap between the SB's and the material of ones' choice - plaster board, OSB or just plain plywood.

Advantage of the later technique, is one can put all your cabling behind and it would also give you a solid substane on to which one can mount fixtures'and fittings.

HTH,

hs

 

[eoinsgaff]

Below is a standard detail for passive house insulation installation.

Its worth noting until I get a sketch of my own proposal

http://i859.photobucket.com/albums/ab15 ... 1262981574

Eoin

 

[MikeG.]

Eoin,

you will have to explain this "passive house" concept to me. What exactly are you trying to achieve.

I built two houses side by side 12 years ago, one of which was a lightweight super-insulated double timber frame construction, with 300mm of insulation in the walls, and a better U value than in your example. The other one, where I live now, has an external timber frame and an inner skin of dense concrete blocks.......200 or 225 of insulation in the external wall, and a lower U value than the lightweight construction for the wall elements. Which one do you think performs better?

Well, in crude financial terms, the timber-only house (lightweight construction, no thermal mass) costs (in 1990 equivalent) around £75 per year to heat, and frequently overheats due to solar gain. The heavyweight construction, with less insulation, costs £40 to £45 per year to heat, and never overheats. The internal temperature is much more stable.......it has never lost or gained a degree celcius in a 24 hour period in 10 years.

So, if you are trying to achieve internal comfort, lower fuel bills or attempt zero space-heating requirements, a timber frame structure alone is not the answer, however well you plan to insulate.

Mike

PS I am not sure that this wall is satisfatory in terms of breathablility, nor that MDF is acceptable as an external skin on a timber frame wall. The local authority, the insurers, and the NHBC would all require proof that this material was suitable, and that a dew-point calculation had been done. Even then, some lenders might have qualms.

There is a breathable sheathing board available to take the place of the MDF outer layer, called Panelvent from Excel Industries, but the whole wall needs designing properly.......not just one element at a time.