How to work out a Hip or Valley raking length.

This is a two part series on how to work out a Hip or Valley raking length for Estimating purposes.

Having done a bit of estimating for large residential builders now, I have come to learn that many estimators do not know how to work out a Hip or Valley length. The matter has recently come up again so in order to get the word out about how to correctly work it out I thought it best to put up a post and an excel spreadsheet demonstrating a method of correctly working them out.

But firstly, and it may seem obvious, why do estimators need to know the Hip and or Valley lengths? Could they not get their Fascia and Gutter supplier or Roofing supplier(Tile or Sheet Metal) to supply them with a quote with the measurements? Of course they could but how would you know they are quoting to you correctly, if you have more then one quote and both match for quantities your probably safe, but what if they differ? You could be building 500 homes a year and they could be supplying you with quotes saying you have an extra 2m of Hip capping on each job. If each lineal meter of hip capping was $15.00, just the roof tile supplier could be getting an extra $15,000 from you each and every year(Are you a builder that has been operating for more then 10yrs?). That is just the start, you also have to pay for your valley irons and valley trimming and some builders pay their carpenters for the lineal meterage of hips as an extra. Those who calculate these simple things the wrong way or rely on a quote for the measurements could be paying more then they need to. It is a fact that I more often then not see these things over allowed rather then correctly allowed, it is primarly the estimator not understainding how to do the calculation correctly to begin with and then adding a little extra “fat” and then also rounding up as well, just to be sure.

So lets get into it shall we. Both a hip or valley length is calculated the same way, this is so because they basically form a corner for a roof and the distance from fascia to apex/ridge does not change be it a Valley(generally an internal corner) or a Hip(generally an external corner).

If you have tried to work it out for yourself before and your thinking to your self the only angle you need to work with Is the roof pitch (in degrees) form the plans, you would be mistaken. This is the common mistake I come across over and over, so don’t feel bad about it you’re not alone. I have found a lot of estimators use the roof pitch factor based off just the main roof pitch to work out the length of their hips and valleys and this leads to over estimating as it is not the right way to work it out.

Consider the following to understand why the pitch of your hip or valley is different to your roof pitch; Your hips and valleys if measured in plan view are longer then your standard truss to the ridge line, this is because they are at 45 degrees to the normal trusses and the distance therefore is further. If your hip or valley was rising at the same pitch as the truss and as we worked out before they are indeed longer, the top of the hip or valley would be higher then the top of the truss. Obviously because your ridge line should be horizontal having your hip higher is going to be an issue.

A common mistake made by estimators is thinking that hips rise at the same degree as normal trusses.

There are three(3) triangles to consider when working out the length.

25 Degree Example Roof

The first triangle would represent half of a normal truss in elevation (side) view.

25 Degree Example Roof

The second triangle would represent the 45 degree angle to the hip or valley in plan view.

25 Degree Example Roof

The third would represent the hip or valley itself in elevation.

25 Degree Example Roof

We now have knowledge of the basic building blocks we require to write the formula to work out the raking length, in the next installment we will go through the math and I will present you with a excel spreadsheet which you can use yourself.

Capitan Morgans Canoe – Straking

~ Continued from “The Skeleton”

So with the skeleton/frame complete I figure out the cuts for the strakes in AutoCAD. Strakes are the panels or planks that make up the skin of a canoe or water craft.

I then print out the design on A3 sheets and tape it to the 4mm marine ply which I’m using for the cladding.

The strakes were then cut out.

Then attached to the skeleton.

I moved outside and started stitching the remaining strakes together.

At this point I had loosely stitched up the majority of the canoe, except for the ends.

I wasn’t confident enough with what I came up with in CAD so I had not cut the ends of the strakes to ensure I could get the curve I wanted. So I had to clamp the ends tight and stitch up my freehand curve inside of the cut that was going to be made. I then freehanded a jigsaw away from the line for later filing and sanding back.

I then put a couple of temporary gunwals and spreader on so I could carry the shell without it collapsing.

Capitan Morgans Canoe – The skeleton

~ Continued from “The First Cut”

So the templates for the skeleton have been cut out and its time to form the strongback to hold them. I had some kitchen laminate board lying around so I decided to box it up and attached the skeleton with droppers down to the strongback. The strongback is there as something to fix to, keep everything straight and be able to do measurements from. How I did it was fairly dodgy as it had about a 10mm bow in it if supported in the center only, but with taking this into account it worked. There are way better examples of how you should do it on the internet, most involve having the strongback inside the frame pieces. You would cutout holes in each piece and slide them over the strongback. Anyway, heres some pictures…
strongback with droppers

strongback with droppers heights correct

Continues with “Straking” ~

Capitan Morgans Canoe – The First Cut

~ Continued from “Construction Begins”

Picking up where I left off, we were transfering the design to the ply.

Great helper transfering the plans to the marine ply

Great helper transfering the plans to the marine ply

Now I needed to predrill a hole on each junction point so the jigsaw could be turned. I offset my holes outside of the frame pieces, but it probably would have been easier to do it exactly on the points. The small amount of the hole that would have been left in the two bulkhead pieces later would have been covered by an epoxy fillet. Because I didn’t think of that at the time, when I began cutting I had to cut small triangles out at each corner to rotate the jigsaw correctly.

Pre-drilling to allow re-alignment of jigsaw

Pre-drilling to allow re-alignment of jigsaw

The First Cut

The First Cut

After a short celebration (VB), I ripped through the rest of the sheet.

Cutting the rest of the frames out.

Cutting the rest of the frames out.

Frames all cut out.

Frames all cut out.

It was starting to look like some progress was being made at this point and I was excited, I recall saying to someone that it would only be a couple more weekends until it was completed. HAHAHA im such a kidder..

Geospatial-Distance Calculators

When working on!LINK BROKEN! I had to figure out how to find the nearest driving schools to the users location. To do this I needed to geocode their address (convert their address to Latitude and Longitude) and check it against my database of driving schools. My database contained the driving schools addresses already geocoded so it was then just a matter of comparing the two. I created a Geocodetestsuite that compares the performance of various ways I have used to calculate the distance.

NOTE 4.11.2016: previously the performance of option 3 took the longest however with the resurrection of my blog I see that the microtime for it is not comparable with option 1. I have not had the opportunity to review why this is.


Geospatial – Redfearn

Someone wanted a php or javascript version of the Redfearn Geospatial Formula, I was bored and wanted a chanllenge so I reverse-engineered an excel spreadsheet from Geoscience Australia to create a php version. You can find the source code and script example here

B¤BMєiStєr the forum member who originally wanted the script updated my version and created the reverse conversion, you can find his site here

Driving School Management System

A long, time ago I put together a Single Driving School management system with PHP and MySQL. It included a Lesson Booking System. Mobile Booking Systems for use with PDA’s or Mobile Phones and it also had SMS Alerts. The site is still going and you can check it out at!No longer my work!.

It was a long time ago and I had an interest in 3D design at the time, note all the images and video I made using Blender, they took a while and were fun to do. I thought they were AWSOME, however my opinion has changed with time, watching the video I made with blender and windows movie maker now is so painfull (check it out – Drivewell Booking System Video).!No longer available! I even started making a 3D game for the site. But as the plugin used for it has long been abandoned it doesn’t work so well on newer systems(if at all now).

Christmas Hampers System – A Joomla! Component

A while ago a client asked for a way to sell christmas hampers online and I was more then happy to accomodate the request.

I ended up creating a Christmas Hamper System for Joomla! that intergrates with Mastercard Internet Gateway System. !no longer available!

Orders can be placed any time of year and repayments deducted automaticaly from clients accounts throughout the year until christmas day when they receive the goods. Repayments can be made weekly, fortnightly, monthly or a once off outright payment. The system divides the total value of the purchase by the amount of repayment periods that are left in the year and deducts the correct amounts from the clients accounts on those days. If a payment is not able to be made due to insufficient funds it is automaticaly retried each day until it succeeds or is manually processed.

The client online purchasing was a streamlined one way process to suit the business process that was outlined for the original project and manual ordering and modifications can be done by staff in the administration section.

What I found was the way you program for Joomla! is well structured, I liked how it was setup to create an installer for the system and how easy it is to apply my custom component to a clients existing installation. If you follow the design pattern they have setout and don’t try to hack in some existing piece of software but rather create something for Joomla! that does what you need, the result is good.

It was a project I really enjoyed and a great way to learn about Joomla!.

Capitan Morgans Canoe – Construction begins!

~ Continued from “Design v2″.

I purchased some British Standards marine ply for the canoe. 4mm for the sides and 9mm for the frame. It was my first investment other then time. The delivery was quick and not to expensive and it was great to see it when I got home from work stacked nicely in the garage. It took a while for me to realise that they must have just thought “Oh, nobodys home! Lets just open up their garage door anyhow and put it inside for safe keeping..”. Not to worry I guess, as nothing was missing.

British Standards Marine Ply

British Standards Marine Ply

Opening up AutoCad to checkout the plans one last time. You can see how I drew the ply sheet and overlayed the sections on it. I then overlayed an A3 sized rectangle onto of them both. I used it to select my exact print areas. Also note I checked out the legal issues with carrying it ontop of my car, it’s legal but I’m still not sure if I will.

After a final check I began printing out my plans for the molds in 1:1 scale, I taped them onto the thicker sheet of ply.

Plans in A3 Printed out

Plans in A3 Printed outFrame Plans taped to plywood

Plans for the molds taped down ready for cutting.

Plans for the molds taped down ready for cutting.

The sheets all line up perfectly when joined exactly edge to edge. Some points are just outside the printable area on the sheets, but by extending the lines im able to form the points correctly.

Transfer of plans to plywood

Transfer of plans to plywood

I left it at that for this particular day.

Continues with “The First Cut” ~