29/08/08

Over the last 2 days we have set out and constructed a half octagon roof. To start of with i thought it was really easy and things were going good but then we found out we had been led in the wrong direction. We decided that 3 sides had to be exactly the same for this to work and that it wasn't the half span. The other 2 sides were the returns going back towards the ridge and it made sense to have them half the length as the other 3. The length of the sides worked out to be about 40.5 percent of the full span but that's not how we figured it out.

Once all the plates were set out we cut the rafters and because the ridges was already up the rafters centered the plates. We then did the 2 hips which had to have a side cut of 17 degrees. after that we did the jack and then cut the last 2 hips. Once the last 2 hips were in we cut trimmers for between 2 of the hips on each side to pick up another 2 jacks. After all that the only thing left to do was cut the under purlins But we had to work out the cuts first. I managed to find out that the down cut and the side cut were the same at 16 degrees.

28/08/08

Yesterday we did a truncated hip on one of our hips on the roof we used for the dormer window. This is where the hip gets cut back which is determined by the jack and then 2 hips come off that. I found this really difficult to get my head around to start with but once i got my head around it it was actually pretty easy. To start with we worked out the spans which are measurements that are right in front of us. Next we worked out our basted hip constant which was rafter constant+normal hip constant divided by 2. Once that was done we cut the jack and we worked out and cut a hip. Using the basted hip we got the height of the jack right so we could mark the hip and cut it where the jack landed. Then we shot the jack into the hip and got the 2 basted hips on. then we had 2 more jacks to get on. i was surprised to find that the top cuts for the other 2 jacks where exactly the same as the hip cuts.

26/08/08

Today we finished our dormer windows. I found today quite challenging because i have never seen one of these been built before so i definitely didn't know where to start building it. once we had our first point things started to come together slowly but they didn't come without a bit of thinking. our start of point was the top of the ridge and we knew it was a 45 degree pitch so we just worked our way down from that. to get the height of the wall we took our overall height and took the halfspan and then took the height of the birdsmouth. Then we build the walls allowing for a window at the front.



After we made sure everything was level we pitched the roof and got the front level with the front plate because it was a gable end. As soon as that was done we cut the valleys and nailed them on then cut the ridge back to the valleys so we could run a trimmer from hip to hip and nail it in to the ridge. After we did that we realised that it would have been better to put the trimmer in first. next i cut the jack which had to be notched around the trimmer. Then we did the valley boards and all the other finishing bits.

20/08/08

Today we spent the whole day on an oblique roof which was done as a class. The roof wasn't as big as some of the others we have done but there was still quite a bit in it. To start off with we leveled 2 benches and then set out plate for rafters to sit on. The plates made a shape that was square at one end and at about 15 degrees on the other end. Once that was done we made sure the whole thing was square and that the 2 longer sides were parallel.

After that we then measured the length of all the sides one of which gave us the half span and wrote them done on the board. We then used those lengths to determine the offsets for the long and short side. The formula to work out the offset on the short side is (short side add Oblique end) take long side divide by 2 and the formula to find out the long side is the same except the long side and short side are swapped around.

Once that was done and the working out was done the cutting was pretty straight forward because we had all the bevels but it was annoying because some needed to be cut on an angle greater than 50 degrees and our saws cant do that. After i got past that the only thing i had trouble with was the creeper shortening but after a bit of problem solving i came up with my own way that was easier and quicker for me to do.

19/08/08

Yesterday we started our brown paper drawing on oblique roofs. The drawing was worked off one of the frames that had been pre made and was drawn to half the size. we each had a different pitch to draw to and mine was 30 degrees. to start off with we drew the outline of the frame and then drew the centring rafters and the jack in. Next we drew in lines for the hips on the oblique end. once that was done we used the red book to find out the true height and the drew a line square off the top of the hip out the height. once that was done it was joined up to the bottom of the hip with another line forming a triangle. the first side made the plan length the second made the height and the last was the true length. we also had the plumb cut angle which was made up where the second and third line meet.

the same was done with both hips before we got onto the common rafters. to start off with we found the middle and put a line square off that the height and then joined it back to the plate. this gave us the plumb cut for the commons and the length. at first i thought all of it was pointless but once i got drawing i got my head around it and saw how useful it is. After doing this i wonder how i thought i could do it without the drawing

23/07/08

Over the last 3 days we have covered a lot of stuff on roofing and have even built a small roof. I really liked building the small roof and thought that it was also done to a pretty good standard considering we are learning as we go. The part that i enjoyed most was the gable because i am still getting used to putting them together and thought it was good to see other ways of doing it. I thought it was good cutting a separate pair of rafters to go under the trimmers and before now i would have never though to do it that way now i think it is good and will be something for me to take back to work. Apart from that i liked doing the scotch valley because its not something you get a lot of and was good for jogging the memory.

During the practical there was also a lot of maths involved with a bit of problem solving for example, i needed to get a 40 and 50 degree angle and i thought it would be a challenge to do it without the protractor so i used the red roofing book. i managed to get the angles for a 40 degree cut but the book stopped at 45 and didn't have 50 so after a bit of thought i decided square a line of the the 40 degree mark and because the 2 angles have to equal 90 it made 50.

30/05/08

Today we spent all day ouside. In the morning we started off with work on our eaves and finished off pulling it all apart including the roof. I liked doing the eaves because i haven't had much experience doing this and it was sort of new to me. First off we started off setting out the boxed eaves. At first i didn't want to do it but once i got into it it was a lot easier than i thought. The most unusual part to me was cutting the notch out for the gutter to sit on but other than that it was all pretty similar.

the other type of eave we did was lined on the rake. this was deffinately a lot different to the eaves we do at work but still not really hard. the only part that i thought could really make things hard was the bottoms of the rafters. That is because all the rafters are a different width it is only a couple of mm and is allowed for with the birds mouth the only thing wrong with that is the way its done makes all the tops level. leaving the bottoms all over the place.