Friday 31 May 2013

Render Colour Chosen

We have decide to render the inside and outside of the house all one colour, to give the illusion that the solid walls are that colour all the way through, so the choice of colour will have a big impact on the look of the house. A light, but warm, yellow is the colour we are aiming for. Originally we were trying to achieve a sand colour until we realised how brown a lot of sand is.  Our light yellow is an idealised version of the colour of sand or chopped hemp fibre.

After initially dismissing the use of Builders brand oxide in 420 Yellow, we reconsidered it when compared to some paint swatches we got from the hardware store the other oxide colours we had tested were too orange or too brown. Our objection to the yellow was its intensity so we tried some very pale versions at 0.2% and 0.4% (Our earlier tests had been 1% and 2% but had been done with unreliable scales. Scales than only measure in 1g increments are not accurate enough when trying to measure a weight of 2 grams ). These tests did not give enough colour to overcome the underlying green grey tinge of the lime render mix. 

Further tests were carried out, both on the hemp wall and on the MgO  board, using 0.6% yellow, 0.8% yellow, 0.6% yellow and 0.2% sundance, and 0.6% yellow and 0.2% sandstone. These tests were measured out using a tiny tube cap as my jewellery scales ordered from e-bay had not yet arrived. Later after I received the jewellery scales, accurate to 0.01g, I found that one capful was 0.45g which when doing 1/40th of a mix was 0.2%. We have done all our render tests on the wall behind where the kitchen cupboards will go, but were running out of room, so we used a hammer and cold chisel to chip off some of the render colours we definitely were not going to use. Pleasingly the render did not pull off easily and was well adhered to the wall, but ultimately came away with minimal damage to the hemp wall underneath. 

Top centre: Chosen colour 0.8% yellow
4th from left: 0.8% yellow on MgO and Top far right wet test of same mix
The further render test colours were all close together which enabled a finer comparison. Even though the colours were close together 0.8% yellow was clearly the best. The lighter yellow (0.6%) lacked sufficient colour, but any darker that 0.8% would have been darker than the “light yellow” colour we wanted.  As it was our chosen colour was darker than the paint swatches we were comparing it to, but it was difficult to make a direct comparison between different products. We checked the 0.8% yellow render against the plywood ceiling and the hardwood window revels and door jambs and the dark grey polished concrete. It was satisfactory against all these materials. We then moved the MgO board outside to see what the render looked like in bright sunlight, and it was still satisfactory. 0.8% yellow has tentatively been chosen. This will translate to 72g of oxide per 9kg bag of render. To check that we have got the measurements correct and can replicate the colour we like we did a further test of 0.8% yellow. We have yet to see this check patch dry.

It is fortunate that we have a render colour, as on the recommendation of our neighbours we met up with John the renderer. He was experienced with a variety of renders and was keen to try a new product, the hemp lime render. We realised it was unlikely that we would be able to achieve a consistent render finish and that it was likely, without experience, that the rendering would take us a long time.  Next time we are on site we have arranged with John to do a section on the inside of one of the wardrobes, so he can see what the product is like to use and work out the finish we want.  We used offcuts of the good ply to finish the ceiling of the robe so it can be sheeted and ready for rendering.

Wardrobe ceiling added
The last two of the cavity sliding door units have been installed. One of the cavity sliders that is not supported at the opening end by a perpendicular wall was a little bit wobbly as when the top and sides were level the bottom of the opening jamb was off the ground. I will have to find some thin masonry anchors to put through the bottom side rails into the concrete floor.

Cavity sliding door units installed
 With the last of the cavity sliding door units in we were able to continue with sheeting the internal walls. I borrowed some fibro cutters from a friend, Martin who has helped out on the build on several occasions. I was amazed that the fibro cutters were easily able to cut through the 8mm MgO board. I just had a little trouble cutting on my marked line and keeping the cut straight. I will practise further with the fibro cutters before I choose my preferred method of cutting the MgO boards.

Internal walls being sheeted with MgO Board
An unusual detail that we discovered while building the walls was that one of the studs at the door opening was set in from the line of the cast hemp wall. This meant that the wall was further out than the stud. When I came to install the door jamb it all worked out very well. I am using 19mm Tassie Oak for my door jambs. I used an angle grinder to cut into the hemp wall to enable me to set the 126mm wide door jamb flush on the stud. When the wall is rendered the 10mm render will come up flush with the door jamb and instead of being a problem this will now give a neat finish.

Hemp wall cut away with angle grinder
Close up of the cut away hemp
The large awning on the north side of the main room had a dip were the two parts of the fascia board were joined. I had been reluctant and unsure how to tackle this problem. My neighbour from home, James, was in Nowra for the weekend and we  recruited him to use his building experience to help us solve this problem. After some thought and discussion the shorter end section was removed and the longer section cut and 2/3rds of it removed so that a single long piece of fascia could be used to replace the pieces removed.

Awning propped and new piece added
 First we used some props to level the remaining pieces of the fascia. It was amazing to see how much the awning had dropped and how much more movement it had in it, since we installed it in January. Further props were added and levelled where the join would be and at the far end, this enabled us to rest the long fascia board on them rather than having to try and hold it. With everything level two batten screws went in at every awning rafter and a cleat was attached to the back of the join of the fascia, which was between to rafters, rather than my previous mistake of jointing the fascia on the rafters and not using a cleat. The result was beautiful. I can look at it proudly and see that it is level. Now I can put the battens on ready for the corrugated roofing to go on. I will also go back and re level and prop the other awnings and leave the props in place until I can put some steel cable in from the awning to the rafters of the roof above, to prevent the awning drooping in the future. 

Straightened awning looking beautiful
 I am still hopeful of being being able able to negotiate an acceptable outcome to the “blue marks on the ply” problem. To avoid any miscommunication and to try and get something happening faster I am now dealing with the distributor, Gunnersons, rather than the local retail supplier I got the ply from. While we resolve this issue it seems we will get on with building the rest of the house and have to leave the main kitchen/living room, bathrooms, laundry and entry unfinished until I can get a product I can use for a ceiling.


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