I would suggest a similar slope for your roof and metal roof as it tends to shed snow well. We have quite a slope on our roof, drops 7 feet in height for each 10 feet in span.

The new side has dimensional roof supports some of which are still open to view. The original house side has old hand sawed tamarack beams and rough milled roof supports.

This house is quite old and was originally just half the size it currently is and so it has a number of structural styles within it. My house has vaulted ceiling through out much of the house and much of the wood supporting my ceiling is still visible. Also the greater the angle of the timber to the snow load the stronger the wood is, ie imagine a boards longitudinal strength (standing upright) as compared to it's span strength.ġ00 pounds per square foot is quite a snow load, we are rated the same here. Look forward to seeing more about your project!Īs well as knowing your span you will also need to determine your slope, the greater the slope the faster is sheds snow weight and the less snow load buildup. It took me a few reads to get my head around it, and I'm sure I'll be reviewing extensively next time I go to use it. The seller should at least be able to ID the species for you, which is some sort of starting point I would expect they will also be able to select and supply suitable wood for rafters and posts ie, let them know that the 4x10s would be for rafters at # span. Of course the actual 'safe' way is spend a b.oatload of money getting a licensed grader to grade the lumber, and a licensed engineer to design the structure.

I use #2 specs for timbers that I mill myself, and do my best to 'grade' them to be above that standard. No problem! In my rush earlier I dropped a couple words, now amended you are no doubt aware that span is the distance a rafter *spans*, not the linear length of the rafter! This could have been why I was so confused to start. Thank you for taking the time to correct my terminology and directing me where to look. I’ll have to see what my math comes up with. My timbers are coming from the Amish (whose buildings have definitely stood up to the worst winters) but I’m not sure I’ll know a grade. To go through these calculations, you need a design load, and specs for your type/grade of wood.Īngela Forget wrote:Thank you! Why didn’t I think to look there *sigh*. Or, you can adjust the rafter size, or both. If you went through the calculations and found younhave insufficient strength, you could then adjust the spacing using a different multiple, to see if that will give you enough strength. In the example calculations, frequency is treated as a fixed value of 2.5ft, so the calculated values for max bending and sheer loads are multiplied by 0.4 at the end of each calculation, because you have only 0.4 times as many rafters as a 1ft spacing. The space between rafters is the rafter spacing, or frequency. Using the terminology in Timber Framing FTROU, simple-span is when there is no center support, while a double-span rafter has a center support. I’m a long time lurker here and you bunch are the most knowledgeable people I know!Īppendix B is the place to focus for this stuff. Does anyone have a good resource or chart that I can understand? Or know the answer? I’ve been reading “timber framing for the rest of us” but I must be missing something. No seismic or wind issues here where I am in upstate NY. The only weight issue we have is snow loads. I see very large timber being used in timber framing for roofs but cannot for the life of me understand the distance between rafters. We are looking to use 6圆 to frame it out (rough cut, possibly 8x8 as we can get this at a reasonable price - pine/hemlock). My husband and I are building a 24x30 strawbale building (non-load bearing). Angela Forget wrote:I have searched the forums and perhaps my terminology is incorrect so I’m hoping someone can weigh in.

Metal roofing rafter spacing