yep, ds7000 has loud piercing siren. how far away from house is the shed? the door sensors/motion sensors work a good distance from ds7000 base; perhaps you can use door sensors in shed and keep ds7000 in house? 1-200 feet are often ok.
I have a 40x60 metal barn a bit too far away and had run 6pair phone cable with power line buried to it; use a pair for the door switches all in series back to garage to ds10 sensor so it is close enough to ds7000 to work consistently.
If you do go the remote ds7000 in shed route, the internal battery back 9v battery only lasts about 2 days (at least in my cases). So I have ds7000 sit on top of 12ah 12v gel cell and feed that directly into the ds7000; it will run LONG time on this before low batt lite comes on....then again if you do need remote batt op at that shed you could put one of harbor freights low cost solar batt charger thing on it to keep it topped off...