Planning Ducting

The HRV Installer called over to the site on Saturday morning, mostly to nose around and say hello (and get some money) and to see what we're about.  From my perspective it was good to discuss exactly how he wants us to prepare the walls for allowing his ducts to pass through.  With ICF, getting a hole in the wall after the fact is not easy - you need reasonably expensive drilling bits, and they get destroyed. So planning anything in advance saves a vast effort later.  The same for the central vacuum, and we'll also put in smaller ducts for routing electrical cables around during the 1st fix.

Rather than placing the ducts in first and pouring concrete around them we'll put in a frame that allows 25mm around the duct.  There are 2 good reasons to do this - 1) the ducts have an insulation jacket around them that might not play nice with the concrete and 2) it allows a little wiggle room for the installer to move the pipes and generally adjust the length etc with less cutting.  So after 10 mins of agreeing the installation followed by an hour talking about rugby another piece of the overall jigsaw has been specified.

Also we're trying to determine the best way to tank the retaining wall.  Initially we were not going to backfill to the wall with earth and just have the drain at the back of the wall.  But the tanking system was concerning me.  The system is to use a bitumen membrane that is waterproof and is stuck to the ICF wall.  This is also taped to the radon barrier to provide a watertight layer wrapping the house.  The membrane is reasonably delicate, so on top of that is hung what is effectively industrial bubble wrap.  Its the same system used across the road.  The problem is that without backfill, the only thing holding it up is sticky pads, and I didn't think they'd last 30+ years.    So - on going back to the supplier the only solution is to backfill the cavity to hold the membrane against the wall - or go with a spray on plastic coating at twice the price.  Backfilling is a messy job but worth it in the end.

Hopefully we'll get the walls poured this week - it seems slow going again but the formwork is largely completed (we now have a doorway) with the delay being detail on how the stairs will sit (we'll be casting the stairs in place with concrete) and need to plan where starter bars that protrude from the wall will have to go.  Its a tricky piece of detail and the architect needs to get his measurements right here.  But - by the end of the week we may finally have an enclosed structure on the site, and getting the next foundations sorted out.

A little short..

The ICF is on going, with more of the basement walls being constructed.  The system we're using is new to the contractor - while the ICF idea is pretty much the same for all there are detail differences, such as distances between ties, sleeve & lintel details etc.  So its been a little slower going now while we learn the best approach of using the maximum material to fit with the dimensions of the house.  We also amend some of the dimensions, 50mm wider may allow easier cutting and could be preferable to 150mm shorter - especially when talking about room area.  Doesn't sound much, but I'd prefer to have it rather than not.

.  This section is the forward room in the basement, and you now see the size of the windows we're putting in down here.  More light is better, and in this section we're looking at having a study and a small home gym - so some welcome relief of contemplating the scenery is needed.  The bottom of the windows will be closer again to the finished floor, as there is 100mm of insulation and 100 of a concrete floor screed to go in.  With underfloor heating, I'd of liked to go thicker with the insulation, but the danger is that the concrete screed can crack on thicker levels of floor insulation.

The ICF Suppliers are also looking to get full up -front payment on the entire quantity of ICF.  They started with an initial amount, which should have been enough to complete the basement, but 'forgot' to leave enough of the sleeves for closing the window/door openings.  So we have to sort them out before pouring the basement.

You can see above the jacks to hold the ICF in place during the pour, as well as a walkway to use when pouring the concrete in the top.

Inside we have the steel rebar - and before pouring more will be placed perpendicular to these horizontal ones.  The inside of the ICF block is ridged - this is to allow the sleeves to slot into these ridges at the openings, but also to increase the internal surface area of the block to give the concrete more area to bind onto.

One question I wondered about was the ability hang heavy items off these walls - such as TV's shelves etc.  The insulating polystyrene itself isn't going to hold anything, but the plastic ties you can see have a head on them inside the polystyrene.  These are evenly spaced every 200mm and you can fix into these - they support pretty much whatever you'd consider fixing to a wall.  Rooted in the concrete, they have plenty of backing.

Central Vacuum

We just decided on another feature in our house, to install a central vacuum system.  This consists of a large vacuum motor in the garage, and ducting distributed around the house.  These terminate into sockets into which you plug a long hose that is the same as any other vacuum (only about 10m in length).

The system activates when you plug the hose into a socket.  This activates the motor and creates a vacuum in the duct system.  There is also a floor pan system for the kitchen, where by you activate the system with your foot and sweep into it from the floor as you would a dustpan.

Its certainly a little bit of an extravagance, but not too much so.  There are genuine benefits to the system, primarily the fact that the really small dust is taken out of the room rather than recycled through the motor back into the air in the room, also the motor is considerably stronger than a standard vacuum cleaner, giving a better clean to the carpet.  You have the less compelling benefit of not having to carry the heavy motor unit around.  All in all it's about even but I think given we have the opportunity to add this in now I'd prefer to do so.

The ducting runs through the finished floor (a sand & cement screed on top of the pre-cast floors) at the same level as the underfloor heating.  We also have to plan to insert runs through the walls and around where the sockets will live in order to minimize the effort of installing the system - with the walls being constructed as I speak we ran close to the wire on this, but with all the other primary issues to get sorted this had to wait until the important stuff got sorted!

ICF Started

The first blocks of ICF are now going onto the basement!  These blocks are forming the front-outside walls and main load-bearing internal walls of the basement.  With these up, we'll be able to walk inside our house for the first time.

The blocks arrive flat-packed from the factory and open up with the plastic internal ties locking them into shape. These are then stacked like lego and steel bars places along them for reinforcing the concrete.  For door and window openings the blocks are simply sawed into the lengths.  No morter or glue is required to hold them together, the blocks fit via a set of plugs on top and sockets on the bottom in a snug fit.

The gap between the polystyrene needs to be shut at the door and window openings, lest the concrete pour out!  Another piece of polystyrene slots between the 2 layers facing into the gap.  Some ICF systems just use wood either, and this has the same effect, the only difference is that the polystyrene sleeves have a better insulation, and it's at the door and window joins that you get a lot of issues with cold-bridging and drafts.  Drafts can be sealed with an expandable foam insulation, but cold-bridging is harder.. its where a conductive material (such as metal) runs from the inside where its warm to the outside where its cold.  This creates a conductive bridge between the 2 environments that bypasses the insulation layers, and leaks heat at a high rate.  It's tricky as where components join it's very easy to create a bridge unknowingly.. an example might be if screws from the inside were to connect to brackets that hold in the windows, and the bracket were to be on the outside.  Its the detail like this that can turn a warm home into a cold one.  In designing the house, there are lots of places these can creep in, and then all it takes is a tradesman to take a short cut and you leak heat (and money!)

So this week should see the build and pour of the basement sections.  I managed to procure a number of ducts from the HRV supplier to place into the walls before we pour the concrete, we'll also add a couple of other 6" or similar ducts to allow electrical cabling and the central vacuum to route through.  This will save drilling through the concrete later (if we've thought of everything).

So far we only have some of the walls complete, waiting on confirmation of the window sizes to properly construct the walls.

The weather right now is fantastic, long may it continue!!  In other news, the bank has re-approved our mortgage and once we re-sign updated documents we should be able to start accessing the money - a massive weight lifted off my shoulders on reading that.

You want money?? - Do you think we're a bank or something??

Cash flow is probably the more stressful part of the build in my opinion, all the other choices are positive in terms of how you want the house to look, or last over time, cost, etc but in general are positive, exciting things to think about.  Cash flow however is wondering who, when and how much you have to pay vs what you have in the bank.  No one like waiting to get paid and I resolved at the start to do my level best to ensure people get paid on time and stay happy.

As stated before the mortgage is paid in arrears, so not until we had the 1st stage complete could we start drawing down the mortgage.  Of course the catch-22 is that you don't want to sign any contracts until the mortgage is 100% available.  So in Nov we finalized and signed the loan agreements, with a 90 day period to draw down the 1st payment.  In that time we had to pick the builder, finailze the price negotiations, find a digger, wait for weather, etc.. but it was more like 6 mths before we were ready to draw down.  In that time we contacted the bank a number of times to ensure that the offer was still good, and if not is there anything we need to do.  All was well.

Until we needed the money that is.  Now the loan offer needs to be redone from scratch.  For anyone who has got a mortgage before there is a lot of documentation that needs to be assembled, all of which cross-confirms your potential to pay.  With the builder having bought the ICF blocks (on our site) he's left at the moment short until we pay the next stage.... and that certainly isn't fair on him.  What should have been a couple of days may turn into a couple of weeks.  And then of course there is the potential for the bank to refuse the application!! But I'm trying not to think of that.  So - all day is a scramble to get documentation together, rooting in various drawers etc.  Funny thing is both Lorraine and I bank day-day with the same bank and they have a more complete picture of our transactions than we do!!  Maybe they are looking to prove that we know what they already know so that they know that we know we can pay the mortgage.  Damn clever.

On the house front, we are delaying a day on starting the ICF walls because I don't know what size door to use internally!  All was fine until I visited a friends house and after a few minutes in there (and acting suspiciously around the door) I realised the door is subtly bigger than standard. It's not a massive thing, but I liked the effect.  It'll also be handy getting things in and out, such as myself when drunk!!  So, while I wait for a poor chap to measure up his doors at home we wait before starting as we need to cut the door openings into the walls as we build up the ICF.  At this stage though more delays are better until we have money to pay for the next bit.

Stress!

Floor poured, 1st Walls up!

After being away for 10 days, the site looks very different again.  Before, we had a layout on the ground and had to imagine how it would look as we went.  Now that floor is concrete, and with the rear walls of the basement up it's gone 3D.  The rear walls are huge to stand beside - over 3.5 metres tall.  A typical room with reasonably high ceilings is about 2.7 metres tall, so we're a metre again up.  For a totally useless piece of information, the weight of just this section is about 340 tonnes!  Also completely useless is the fact that if you had a big enough crane, you could actually lift the entire structure up - the radon barrier completely separates it from the ground underneath.

There is an access panel for brining in the live ESB - it comes in at the base, in the floor, up through the wall into the meter box, then back through the wall up to the top of the wall.  This can then route into the suspended ceiling that will hang from the roof and route in the far corner in the picture (left most corner) - it comes in from picture right.

The wall itself is watertight (due to the amount of cement in the concrete) but the back of it nearest the wall needs to be tanked - that is made watertight (more so).  This involves placing a layer of waterproof membrane all along the wall and bonding it to the Radon barrier that is also waterproof. You can see the tight space that lies in here

The radon barrier is cleaned off and wrapped up tight to the wall and the membrane overlaps it.  Also in here we need to place a drain, as even when it's dry as today the back wall is weeping water.  A layer of drainage stone goes in, another of the yellow land-drainage pipes goes on top, and we fill in with more stone to above where the wall is damp, about 1.2 metres.  Where this picture is now will eventually be right under the main house itself.

We marked out the internal ICF walls as well, these will start to be assembled on Wednesday, and will form the rest of the outer walls, as well as some load bearing internal ones.  By Saturday, we're likely to be ready to pour these with concrete, and we'll have the first section of the house structure complete.

Before we pour, there are a number of services that need to transit through these walls, and we'll place pipes where they cross through before pouring.  This prevents us later having to drill though the mass concrete. All in all, now most of the tricky stage is complete, and with hopefully a few weeks of fine weather that you expect as all the poor students sit down to write exams, we can get cracking and make a good push on the build.  Finally - our nutritious grass and diesel fumes are having a positive effect on the local wildlife with a new lawnmower gambling about, no fear of our grass getting out of hand.

Radon-on

The weekend sees the floor coming along - the Radon barrier is down, steel cages are all in and the first set of pipes have been placed by the plumber.  With the radon barrier providing a sharp contrast in colour, the house outline is even clearer to see

On the left-hand side is where the basement bathroom will be, and the 2 long pipes in the center allow for cables to be run from the back where the electrical switchboard will be to the front for whatever purpose - outside sockets, gate intercom etc.  Great idea from the engineer and will save us a lot of bother in future when we wish to add or change any such cabling.  Of course, all I can think of is that it'll be the perfect way for Rats to get in as well, perhaps we should have made the diameter big enough to flush them through with a cat every so often.

With Monday being a bank holiday, realistically it will be Wednesday when the floor is poured.  With that finished, we'll have finally reached a stage where we can access our mortgage, and fingers crossed that it will still be there.  We have all the application signed and returned, but until you draw the funds it's still a little up in the air, and since we signed in January (with 30 days to draw down) its a little bit of worry in case anything has changed.  Our broker & bank have it on hold, but who knows.  It's a funny way of providing a build-mortgage, but you don't get any money upfront to start the project.  As you build (and add value to the site) then the bank pays you in arrears for that value.  This leaves you having to manage a tight cash flow, and all the unforeseeable extras serve to tighten the screw.

So by Wednesday I hope to have another milestone reached.  Again the clock here is to get weather-tight by the end of September (I won't say Summer) to allow us to work inside over Winter.