Bear with us, we know this doesn\u2019t sound the most exciting topic for a blog but actually, it is pretty interesting (well we think so anyway!) and it\u2019s important to know when building your own home or extension about the core structure of the build.<\/p>\n
Q represents the initial of the Latin name for Oak – Quercus<\/td>\n
The second character indicates the product. P stands for beams (B boules, S selected boards and so on)<\/td>\n
This relates to the quality grade with A being the highest, exceptional quality. 1.2.3.4 is the decreasing quality<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
So,\u00a0 you know what Q P A grading means, now to confuse you further…although the sawmill uses the Q P A system, our carpenters also grade the timber when it arrives at our yards using the \u2018Carpenter Oak British specification\u2019. The timber grading we have devised is far superior to the Q P A system. Here\u2019s the comparison:<\/p>\n
\n\n
\n
<\/td>\n
Carpenter Oak \n<\/strong><\/td>\n
European spec Q P A<\/strong><\/td>\n<\/tr>\n
\n
Live knot size<\/strong><\/td>\n
25%<\/td>\n
30%<\/td>\n<\/tr>\n
\n
Dead knots<\/strong><\/td>\n
Up to 25mm<\/td>\n
Up to 25mm<\/td>\n<\/tr>\n
\n
Slope of grain<\/strong><\/td>\n
1:10<\/td>\n
1:10<\/td>\n<\/tr>\n
\n
Wane<\/strong><\/td>\n
Acceptable if it can be removed by a camfer<\/td>\n
15%<\/td>\n<\/tr>\n
\n
Sapwood<\/strong><\/td>\n
Acceptable if it can be removed by a camfer<\/td>\n
15%<\/td>\n<\/tr>\n
\n
Bow (over 2m)<\/strong><\/td>\n
14mm<\/td>\n
16mm<\/td>\n<\/tr>\n
\n
Spring (over 2m)<\/strong><\/td>\n
14mm<\/td>\n
16mm<\/td>\n<\/tr>\n
\n
Twist (over 2m)<\/strong><\/td>\n
14mm<\/td>\n
1mm per 25mm width<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n
Successful timber frame carpentry is dependent upon the assessment, grading and orientation of each individual timber for its aesthetics and structural properties. The quality and appearance of the timber that we use in our frames will help to determine the structural integrity, durability, longevity and ultimately the value of the structures. This is why we use a more stringent system to Q P A timber grading.<\/p>\n
Our carpenters grade all timber when it is delivered to our framing yard and each timber is checked by our carpenters during the framing process. Timbers can be, and are rejected, at any time during the framing. The cost of replacing a timber incorporated into a timber frame building is very high (especially if that building has been completed on site) and we endeavour to remove any such problems at the source.<\/p>\n