When we do a load of laundry (1st floor), the basement tub backs up. Is there some sort of attachment we can put on the drain pipes to slow down the flow or only allow water to flow in one direction from the tub?

I am worried that it is a problem with improper instillation of the tub/drain in the basement or the drain line from the washing machine.

Hello anyway. Have you had this problem from the start? Or did this just start accuring ?
If it just recently started then you probably need to rooter out your sewer line. If its always been that way, then there's a problem with the drainage system as you suspect there is.
Do you have a sump system in the basement? If you do then there may be an issue with the pump . Get back to us and lets help you figure this out . Goodluck ---Zeke---

When we do a load of laundry (1st floor), the basement tub backs up. Is there some sort of attachment we can put on the drain pipes to slow down the flow or only allow water to flow in one direction from the tub?

I am worried that it is a problem with improper instillation of the tub/drain in the basement or the drain line from the washing machine.
As far as we know (4 months) this has always been a problem. This is a 60 yr old house and we just moved in, it has had some renovations over the years including a newer bathroom, and the tub I'm talking about is a jaccuzzi.

As far as I know the main drain to the house is in the opposite side of our upstairs laundry and basement kitchen sink, bathtub and bathroom sink. So I assume they are all leading to one "newer" drain.

We have no sump system.

When we do a load of laundry (1st floor), the basement tub backs up. Is there some sort of attachment we can put on the drain pipes to slow down the flow or only allow water to flow in one direction from the tub?

I am worried that it is a problem with improper instillation of the tub/drain in the basement or the drain line from the washing machine.
My neighbor had the same problem as you. We cured it by installing a check valve on the laundry tray drain line and by gluing a PVC Desanco Fitting,(see image)on the washer stand pipe making it a closed system.
The check valve prevented the washer from backing up into the sink and the compression fitting on the standpipe forced the discharge out into the main.
Good luck, Tom