Use long time averaging periods for both the pre-test baseline house pressure reading and for the CFM50 reading.  To do this, use the baseline function on the DG-700 and let it count up for 30 to 60 seconds.  Also use the CFM@50 mode on the DG-700 and when the building is at about 50 Pascals, change the time averaging period to Long and allow it to display the long term average for 30 to 60 seconds before recording the CFM50 number.   If the wind speed is greater than 5 mph, we recommend that you do a multi-point test using our TECTITE software.  The TECTITE software has the ability to calculate the accuracy and repeatability of the test, so you will have an added confidence in your readings.