Hi, I am new here and just wondering how far apart my registers should be from each other. It is a new system in a new home. The registers will be on the floor coming from a crawl space foundation. Is there a UMC code on spacing for supply registers. I have two floors, but the first floor is made of log walls, so I don't think they will be able to get any registers upstairs, so I will give the sq ft for just the down stairs. It is 1232sq ft with one bedroom and the rest is bathroom, greatroom and kitchen. I saw in the UBC code 310.11 that I need 3 feet of heat maintained at 70' for all habitable rooms. I also have two upstair bedrooms. The wall on the first floor are all log, not sure if I have to get registers in each room to comply. I will also have a gas fireplace in the great room so I was hoping this might offset the code for having to have registers upstairs. I am not sure if I can get an answer since I can't show my plans, but hopefully someone understands. I am just trying to find out if there is a code for register supply spacing placements or if there is an optimum spacing used for heating a home and if I need them in each room upstairs to comply with the UBC . I suppose a lot might matter on the heater size, which I don't know yet, but hopefully I can get some help from the pros here. Thanks a lot.

I need 3 feet of heat maintained at 70' for all habitable rooms.?

That does not make sense. Is it 70 degrees?

Usually you used a duct calculator to figure the size in any room for the pipe/register size.
Usually the registers are placed in from of the windows to blanket that area with heat. Use a duct calculator and also a manual J to make sure you will have enough heat/AC for the size of the structure.

In the UBC code which I quoted, it says, That Dwelling units, guest rooms and congregate residences shall be provided with heating facitlities capable of maintaining a room temp. of 70' (degrees) at a point 3 feet above the floor in all habitable rooms, ( sorry for not saying it was degrees in my earlier post , but my computer does not have a little tiny circle to put next to the number and I just assumed that a HVAC contractor would have seen this 310.11UBC code term before. Sorry, I will try to be more clear).
I am not looking for the duct size, or the size of my heater. In my post I said I was looking for the spacing from register to register and if there is any codes to that, such as spacing for a 2'' x 12'' rafter at a 4&12 pitch, There must be some sort of logical spacing of registers that HVAC Contractors go by? Such as 10 feet apart from each other or something like this. I know about Manual J and D, but before I go and spend 60.00 for each I thought It would be easier to come here and ask Contractors what they usually would space a register at in a room that is 28'x40'. Thanks again for your reply hvac1000

Calculate how many registers you need for the room after figuring out how much heat loss the room would have!

You cannot guess at this stuff. As far a spacing goes even spacing seems to work well and place at least one register in front of the windows. I really do not think that anyone can give you the proper answer withour seeing the plans with wall and ceiling insulation factors,floor coverings,orientation of windows (north south east west? ) window size/type. And more.

Next in order to figure spacing you have to know how many duct runs you are going to need and that is determined by the figures from above and the size of your pipes and register boxes and grills/floor register coverings. When you ask a generic question you get a generic answer.

In my area we do not use UBC so how would I know what it says. I am a certified mechanical inspector in this state and also give classes for fun since I am retired. There is no generic answer for your question.

When you ask a generic question you get a generic answer. I Thought everyone used the UBC code. That is why it is called the UNIVERSAL BUILDING CODE. I don't think my question was generic, I just don't think you know how to read. I really doubt that you teach classes if you don't know the UBC codes. They have been around for a long time and you must be from China if you are in the industry and have never seen UBC CODE 310.11 it's the only one in the UBC that deals with HVAC. I doubt also that you're an inspector if you can't even quote the Code. Maybe that is why most of the inspectors out there are idiots, because they don't know the codes and then get on here and try to give advice. Stay retired and stop trying to give advice. You're an idiot.

We use the OBBC here. Sorry about your personal problems and good luck with finding your answers.